Himalayas
The Himalayas, also Himalaya, (/ˌhɪməˈleɪ.ə/ or /hɪˈmɑːləjə/; Sanskrit, hima (snow) + ālaya (dwelling), literally, "abode of the snow"[1]) is a mountain range in Asia separating the plains of the Indian subcontinent from the Tibetan Plateau. ACER Travelmate 4152nlci Laptop CPU Cooling Fan
The Himalayan range is home to the planet's highest peaks, including the highest, Mount Everest. The Himalayas include over a hundred mountains exceeding 7,200 metres (23,600 ft) in height. HP pavilion DV7-1000 Laptop Keyboard
By contrast, the highest peak outside Asia—Aconcagua, in the Andes— is 6,961 metres (22,838 ft) tall.[2] The Himalayas have profoundly shaped the cultures of South Asia. Many Himalayan peaks are sacred in both Buddhism and Hinduism. HP Mini 110-1120LA Laptop Keyboard
Besides the Greater Himalayas of these high peaks there are parallel lower ranges. The first foothills, reaching about a thousand meters along the northern edge of the plains, ACER Aspire 5742 Laptop Keyboard
are called the Sivalik Hills or Sub-Himalayan Range. Further north is a higher range reaching two to three thousand meters known as the Lower Himalayan or Mahabharat Range. ACER TravelMate 4100 Laptop Keyboard
The Himalayas abut or cross five countries: Bhutan, India, Nepal, China, and Pakistan, with the first three countries having sovereignty over most of the range.[3] The Himalayas are bordered on the northwest by theKarakoram and Hindu Kush ranges, HP Envy 15 Laptop Keyboard
on the north by the Tibetan Plateau, and on the south by the Indo-Gangetic Plain.
Three of the world's major rivers, the Indus, the Ganges, and the Tsangpo-Brahmaputra all rise near Mount Kailash to cross and encircle the Himalayas. Their combined drainage basin is home to some 600 million people. DELL Vostro 3550 Laptop Keyboard
Lifted by the collision of the Indian tectonic plate with the Eurasian Plate,[4] the Himalayan range runs, west-northwest to east-southeast, in an arc 2,400 kilometres (1,500 mi) long. Its western anchor, ACER Aspire 5810T-8929 Laptop Keyboard
Nanga Parbat, lies just south of the northernmost bend of Indus river, its eastern anchor, Namcha Barwa, just west of the great bend of the Tsangpo river. The range varies in width from 400 kilometres (250 mi) in the west to 150 kilometres (93 mi) in the east. Compaq Presario CQ42-228LA Laptop Keyboard
The flora and fauna of the Himalayas vary with climate, rainfall, altitude, and soils. The climate ranges from tropical at the base of the mountains to permanent ice and snow at the highest elevations. HP Pavilion DV7-3065dx Laptop Keyboard
Owing to the mountains’ latitude near the Tropic of Cancer, the permanent snow line is among the highest in the world at typically around 5,500 metres (18,000 ft).[5] In contrast, DELL E141395 Laptop Keyboard
equatorial mountains in New Guinea, theRwenzoris and Colombia have a snow line some 900 metres (2,950 ft) lower.[6] The amount of yearly rainfall increases from west to east along the southern front of the range. ACER Aspire 7745G Laptop Keyboard
This diversity of altitude, rainfall and soil conditions combined with the very high snow line supports a variety of distinct plant and animal communities. For example the extremes of high altitude (low atmospheric pressure) combined with extreme cold allow extremophile organisms to survive.[7]
The unique floral and faunal wealth of the Himalayas iCompaq Presario CQ42-228LA Laptop Keyboard
s undergoing structural and compositional changes due to climate change. The increase in temperature may shift various species to higher elevations. The oak forest is being invaded by pine forests in the Garhwal Himalayan region. HP G72-c55DX Laptop Keyboard
There are reports of early flowering and fruiting in some tree species, especially rhododendron, apple and Myrica esculenta. The highest known tree species in the Himalayas isJuniperus tibetica located at 4,900 metres (16,080 ft) in Southeastern Tibet.[8] Lenovo 3000 Y510a 15303 laptop keyboard
The Himalaya are among the youngest mountain ranges on the planet and consist mostly of uplifted sedimentary andmetamorphic rock. According to the modern theory of plate tectonics, HP Pavilion dv6-2030ev laptop keyboard
their formation is a result of a continental collision or orogeny along the convergent boundary between the Indo-Australian Plate and the Eurasian Plate. The Arakan Yoma highlands in Myanmar and the Andaman and Nicobar Islands in the Bay of Bengal were also formed as a result of this collision. DELL Inspiron N4050 laptop keyboard
During the Upper Cretaceous, about 70 million years ago, the north-moving Indo-Australian Plate was moving at about 15 cm per year. About 50 million years ago, this fast moving Indo-Australian plate had completely closed the Tethys Ocean, HP Pavilion dv6-2060ea laptop keyboard
the existence of which has been determined by sedimentary rocks settled on the ocean floor, and the volcanoesthat fringed its edges. Since both plates were composed of low density continental crust, HP Pavilion dv6-2155ee laptop keyboard
they were thrust faulted andfolded into mountain ranges rather than subducting into the mantle along an oceanic trench.[4] An often-cited fact used to illustrate this process is that the summit of Mount Everest is made of marine limestone from this ancient ocean.[9] DELL Latitude E5410 laptop keyboard
Today, the Indo-Australian plate continues to be driven horizontally below the Tibetan plateau, which forces the plateau to continue to move upwards. The Indo-Australian plate is still moving at 67 mm per year, ACER TravelMate 3020 laptop keyboard
and over the next 10 million years it will travel about 1,500 km into Asia. About 20 mm per year of the India-Asia convergence is absorbed by thrusting along the Himalaya southern front. This leads to the Himalayas rising by about 5 mm per year, making them geologically active. ACER TravelMate 2403 Series laptop keyboard
The movement of the Indian plate into the Asian plate also makes this region seismically active, leading to earthquakes from time to time. HP pavilion DV7-1029eg laptop keyboard
During the last ice age, there was a connected ice stream of glaciers between Kangchenjunga in the east and Nanga Parbat in the west.[10] In the west, the glaciers joined with the ice stream network in the Karakoram, and in the north, joined with the former Tibetan inland ice. SONY VAIO VGN-AW25GJ laptop keyboard
To the south, outflow glaciers came to an end below an elevation of 1,000–2,000 metres (3,300–6,600 ft).[10][11] While the current valley glaciers of the Himalaya reach at most 20 to 32 kilometres (12 to 20 mi) in length, several of the main valley glaciers were 60 to 112 kilometres (37 to 70 mi) long during the ice age.[10] SONY VAIO PCG-F50/BP laptop keyboard
The glacier snowline (the altitude where accumulation and ablation of a glacier are balanced) was about 1,400–1,660 metres (4,600–5,450 ft) lower than it is today. Thus, the climate was at least 7.0 to 8.3 °C (13 to 15 °F change) colder than it is today.[12] DELL Inspiron 1750 Laptop Keyboard
The easternmost Himalayan rivers feed the Ayeyarwady River, which originates in eastern Tibet and flows south throughMyanmar to drain into the Andaman Sea.
The Salween, Mekong, HP 448159-001 Laptop Keyboard
Yangtze and Huang He (Yellow River) all originate from parts of the Tibetan plateau that are geologically distinct from the Himalaya mountains, and are therefore not considered true Himalayan rivers. DELL Latitude E6500 Laptop Keyboard
Some geologists refer to all the rivers collectively as the circum-Himalayan rivers.[14] In recent years, scientists have monitored a notable increase in the rate of glacier retreat across the region as a result of global climate change.[15] DELL Studio 1737 Laptop Keyboard
For example, Glacial lakes have been forming rapidly on the surface of the debris-covered glaciers in the Bhutan Himalaya during the last few decades. Although the effect of this will not be known for many years, DELL Inspiron 1521 Laptop Keyboard
it potentially could mean disaster for the hundreds of millions of people who rely on the glaciers to feed the rivers of northern India during the dry seasons.[16] Some of the lakes present a danger of aglacial lake outburst flood. The Tsho Rolpa glacier lake in the Rolwaling Valley is rated as the most dangerous in Nepal.[17][18] DELL Alienware M17xR2 Laptop Keyboard
The Himalayan region is dotted with hundreds of lakes. Most lakes are found at altitudes of less than 5,000 m, with the size of the lakes diminishing with altitude. Tilicho lake in Nepal in the Annapurna massif is one of the highest lakes in the world. Pangong Tso, HP 519265-001 Laptop Keyboard
which is spread across the border between India and China, and Yamdrok Tso, located in central Tibet, are amongst the largest with surface areas of 700 km², and 638 km², respectively. Other notable lakes include Gurudogmar lake, in North Sikkim, and Tsongmo lake, near the Indo-China border in Sikkim. COMPAQ Presario C700 Laptop Keyboard
The mountain lakes are known to geographers as tarns if they are caused by glacial activity. Tarns are found mostly in the upper reaches of the Himalaya, above 5,500 metres.[19] Lenovo Thinkpad T420 Laptop Keyboard
The Himalayas have a profound effect on the climate of the Indian subcontinent and the Tibetan plateau. They prevent frigid, dry Arctic winds blowing south into the subcontinent, TOSHIBA Satellite A305 Laptop Keyboard
which keeps South Asia much warmer than correspondingtemperate regions in the other continents. It also forms a barrier for the monsoon winds, keeping them from traveling northwards, and causing heavy rainfall in the Terai region. Compaq Presario CQ57 Series Laptop Keyboard
The Himalayas are also believed to play an important part in the formation of Central Asiandeserts, such as the Taklamakan and Gobi.[20] Lenovo 39T7417 Laptop Keyboard
In Hinduism, the Himalaya have also been personified as the god Himavat, the God of snow, who is mentioned in theMahabharata. He is father of Ganga and Saraswati, who became rivers, and Parvati, who married Shiva.[21] DELL Vostro 3450 Laptop Keyboard
Several places in the Himalaya are of religious significance in Hinduism, Jainism, Sikhism, Buddhism, and Islam. A notable example of a religious site is Paro Taktsang, where Padmasambhava is said to have founded Buddhism inBhutan.[22]
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There were over 6,000 monasteries in Tibet.[23] The Tibetan Muslims had their own mosques in Lhasa and Shigatse.[24] HP Pavilion DV6-1002tx Laptop Keyboard
The Tropic of Cancer, also referred to as the Northern tropic, is the circle of latitude on theEarth that marks the most northerly position at which the Sun may appear directly overhead at itszenith. HP 519265-001 Laptop Keyboard
This event occurs once per year, at the time of the June solstice, when the Northern Hemisphere is tilted toward the Sun to its maximum extent. It currently (Year 2013) lies at 23° 26′ 15.143″ north of the Equator.[1] DELL Precision M4500 Laptop Keyboard
Its Southern Hemisphere counterpart, marking the most southerly position at which the Sun may appear directly overhead, is the Tropic of Capricorn. These tropics are two of the five major degree measures or major circles of latitude that mark maps of the Earth, DELL PK130801B00 Laptop Keyboard
besides the Arctic and Antarctic Circles and the Equator. The positions of these circles of latitude (other than the Equator) are dictated by the tilt of the Earth's axis of rotation relative to the plane of its orbit. HP Pavilion DV6-1030us Laptop Keyboard
The imaginary line is called the Tropic of Cancer because when the Sun reaches the zenith at this latitude, it is entering the tropical sign of Cancer (summer solstice). HP Probook 4520S Laptop Keyboard
When it was named, the Sun was also in the direction of the constellation Cancer (Latin for crab). However, this is no longer true due to the precession of the equinoxes. According toInternational Astronomical Union boundaries, the Sun now is in Taurus at the June solstice. SONY 147977821 Laptop Keyboard
According to sidereal astrology, which divides thezodiac into 12 equal parts, the Sun is in Gemini at that time. However, according to tropical astrology, which divides the ecliptic in twelve 30° sectors, SONY 147963021 Laptop Keyboard
starting with the vernal equinox, the Sun is always entering Cancer at this time, as the Earth's axial tilt is most inclined towards the Sun. The word "tropic" itself comes from the Greek tropos, meaning turn, referring to the fact that the sun appears to "turn back" at the solstices. SONY VAIO VGN-CS16M/P laptop keyboard
The Tropic of Cancer currently (Epoch 2012) lies 23° 26′ 16″ [2] north of the Equator. Its position is not fixed, but varies in a complicated manner over time. It is presently drifting south at the rate of almost half a second (0.47″) of latitude per year (it was at exactly 23° 27' in year 1917).[3] See circles of latitude for further information. IBM Thinkpad R40 laptop keyboard
North of Tropic of Cancer are the subtropics and the North Temperate Zone. The equivalent line of latitude south of the Equator is called the Tropic of Capricorn, and the region between the two, centered on the Equator, is the tropics. HP Pavilion DV7-3186cl laptop keyboard
Starting at the Prime Meridian and heading eastwards, the Tropic of Cancer passes through:
Excluding cooler highland regions in China, the climate at the Tropic of Cancer is generally hot and dry except for easterly coastal areas whereorographic rainfall can be very heavy, in some places reaching 4 metres (160 in). SONY VAIO VGN-N320E/W laptop keyboard
Most regions on the Tropic of Cancer experience two distinct season: an extremely hot summer with temperatures often reaching 45 °C (113 °F) and a warm winter with maxima around 22 °C (72 °F). Lenovo ThinkPad Edge E520 laptop keyboard
Most land on or near the Tropic of Cancer is part of the Sahara Desert, whilst to the east the climate is torrid monsoonal with a short wet season from June to September and very little rainfall for the rest of the year. HP Pavilion dv6-2170eo laptop keyboard
The highest mountain on or adjacent to the Tropic of Cancer is Yushan in Taiwan; though it had glaciers descending as low as 2,800 metres (9,190 ft) during the Last Glacial Maximum TOSHIBA Satellite L655-S5153 laptop keyboard
, none survive and at present no glaciers exist within 470 kilometres (290 mi) of the tropic of Cancer; the nearest currently surviving are the Minyong and Baishui in the Himalayas to the north and on Iztaccíhuatl to the south. HP Pavilion DV7-3067cl laptop keyboard
The Southern Hemisphere is part of a rotating astronomical body that lies south of the equator. The word hemisphere(from the Greek word σφαιρα (sphere) +ημι (half)) literally means 'half ball' or "half sphere". It is also that half of the celestial sphere south of the celestial equator. HP Pavilion DV7-3180us laptop keyboard
On Earth the Southern Hemisphere contains all or parts of four continents (Antarctica, Australia, about 9/10 of South America and the southern third of Africa), four oceans (Indian, South Atlantic, Southern, and South Pacific) and most of Oceania. SONY VAIO VGN-FW11S laptop keyboard
Several islands off the Asian continental mainland are also in the Southern Hemisphere. Due to the tilt of Earth's rotation relative to the Sun and the ecliptic plane, HP Pavilion DV6-1122us laptop keyboard
summer is from December to March and winter is from June to September. September 22 or 23 is the vernal equinox and March 20 or 21 is the autumnal equinox. HP Pavilion dv6-2170ee laptop keyboard
In the Southern Hemisphere the sun passes from east to west through the north, although north of the Tropic of Capricorn the mean sun can be directly overhead or due south at midday. SONY VAIO VGN-FS315M laptop keyboard
The Sun rotating through the north causes an apparent right-left trajectory through the sky unlike the left-right motion of the Sun when seen from the Northern Hemisphere as it passes through the southern sky. DELL PK130801B00 laptop keyboard
Sun-cast shadows turn anticlockwise throughout the day and sundials have the hours increasing in the anticlockwise direction. During solar eclipses viewed from a point to the south of the Tropic of Capricorn the Moon moves from left to right on the disc of the Sun (see, for example, TOSHIBA Satellite L655-S5163 laptop keyboard
photos with timings of the Solar eclipse of November 13, 2012), while viewed from a point to the north of the Tropic of Cancer (i.e., in the Northern Hemisphere) the Moon moves from right to left during a solar eclipses. HP Pavilion dv5t-1200se CTO laptop keyboard
Cyclones and tropical storms spin clockwise in the Southern Hemisphere (as opposed to anticlockwise in the Northern Hemisphere) due to the Coriolis effect. COMPAQ Presario C700 Laptop Keyboard
The southern temperate zone, a subsection of the Southern Hemisphere, is nearly all oceanic. This zone includes all of Uruguay, Lesotho, Swaziland, and New Zealand; most of Chile, Argentina, South Africa, andAustralia; and parts of Paraguay, Brazil, Namibia, Botswana, Mozambique, and Madagascar. HP G72-b60US Laptop Keyboard
The South Pole is oriented towards the galactic centre and this, combined with clearer skies, makes for excellent viewing of the night sky from the Southern Hemisphere with brighter and more numerous stars. DELL INSPIRON 1464 Laptop Keyboard
Forests in the Southern Hemisphere have special features which set them aside from the Northern Hemisphere. Both Chile and New Zealand share, for example, unique beech species or Nothofagus. DELL XPS 15 L502X Laptop Keyboard
The eucalyptus is native to Australia but has now gone on to be planted in Southern Africa and Latin America for pulp production and, increasingly, biofuel uses.
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. DELL Vostro 1015 Laptop Keyboard
It may be a change in average weather conditions, or in the distribution of weather around the average conditions (i.e., more or fewer extreme weather events). Climate change is caused by factors that include oceanic processes (such as oceanic circulation), biotic processes, HP 643263-001 Laptop Keyboard
variations insolar radiation received by Earth, plate tectonics and volcanic eruptions, and human-induced alterations of the natural world; these human-induced effects are currently causing global warming, and "climate change" is often used to describe human-specific impacts. SAMSUNG N140 Laptop Keyboard
Scientists actively work to understand past and future climate by using observations and theoretical models. A climate record -- extending deep into the Earth's past -- has been assembled, and continues to be built up, TOSHIBA Mini NB 505-SP0160 Laptop Keyboard
based on geological evidence from borehole temperature profiles, cores removed from deep accumulations of ice, floral andfaunal records, glacial and periglacial processes, stable-isotope and other analyses of sediment layers, and records of past sea levels. IBM 42T4026 laptop keyboard
More recent data are provided by the instrumental record. General circulation models, based on physics, are often used in theoretical approaches to match past climate data, make future projections, Lenovo 3000 G530 4151 laptop keyboard
and link causes and effects in climate change.
The most general definition of climate change is a change in the statistical properties of the climate system when considered over long periods of time, regardless of cause.[1] Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, do not represent climate change. Packard Bell Easynote TM98 laptop keyboard
The term sometimes is used to refer specifically to climate change caused by human activity, as opposed to changes in climate that may have resulted as part of Earth's natural processes.[2] SONY VAIO VGN-N21E/W laptop keyboard
In this sense, especially in the context of environmental policy, the term climate change has become synonymous withanthropogenic global warming. Within scientific journals, HP Pavilion DV7T-4100 laptop keyboard
global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels will affect.[3] SONY VAIO VGN-FS215E laptop keyboard
On the broadest scale, the rate at which energy is received from the sun and the rate at which it is lost to space determine the equilibrium temperature and climate of Earth. This energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions. SONY Vaio PCG-K23 laptop keyboard
Factors that can shape climate are called climate forcings or "forcing mechanisms".[4] These include processes such as variations in solar radiation, variations in the Earth's orbit, mountain-building and continental drift and changes in greenhouse gas concentrations. DELL NSK-DB301 laptop keyboard
There are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the climate system, such as the oceans and ice caps, respond slowly in reaction to climate forcings, while others respond more quickly. TOSHIBA P205-S7469 laptop keyboard
Forcing mechanisms can be either "internal" or "external". Internal forcing mechanisms are natural processes within the climate system itself (e.g., thethermohaline circulation). External forcing mechanisms can be either natural (e.g., changes in solar output) or anthropogenic (e.g., increased emissions of greenhouse gases).
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a sudden cooling due to airbornevolcanic ash reflecting sunlight), slow (e.g. thermal expansion of warming ocean water), or a combination (e.g., sudden loss of albedo in the arctic ocean as sea ice melts, SONY VAIO VGN-NW110D laptop keyboard
followed by more gradual thermal expansion of the water). Therefore, the climate system can respond abruptly, but the full response to forcing mechanisms might not be fully developed for centuri SONY VAIO VGN-N250E/B laptop keyboard
Natural changes in the components of Earth's climate system and their interactions are the cause of internal climate variability, TOSHIBA 9J.N9282.W01 laptop keyboard
or "internal forcings." Scientists generally define the five components of earth's climate system to include atmosphere, hydrosphere, cryosphere, lithosphere (restricted to the surface soils, rocks, and sediments), and biosphere.[5] SONY KFRMBA151B laptop keyboard
The ocean is a fundamental part of the climate system, some changes in it occurring at longer timescales than in theatmosphere, massing hundreds of times more and having very high thermal inertia (such as the ocean depths still lagging today in temperature adjustment from the Little Ice Age).[clarification needed][6] TOSHIBA Satellite l25-s1196 laptop keyboard
Short-term fluctuations (years to a few decades) such as the El Niño-Southern Oscillation, the Pacific decadal oscillation, the North Atlantic oscillation, and the Arctic oscillation, HP Pavilion DV6-1205ee laptop keyboard
represent climate variability rather than climate change. On longer time scales, alterations to ocean processes such as thermohaline circulation play a key role in redistributing heat by carrying out a very slow and extremely deep movement of water and the long-term redistribution of heat in the world's oceans. SAMSUNG Q320 laptop keyboard
Life affects climate through its role in the carbon and water cycles and such mechanisms as albedo, evapotranspiration,cloud formation, and weathering.[7][8][9] Examples of how life may have affected past climate include: glaciation 2.3 billion years ago triggered by the evolution of oxygenic photosynthesis,[10][11] TOSHIBA Satellite M645-S4070 Laptop Keyboard
glaciation 300 million years ago ushered in by long-term burial of decomposition-resistant detritus of vascular land plants (forming coal),[12][13] HP Probook 4515S Laptop Keyboard
termination of the Paleocene-Eocene Thermal Maximum 55 million years ago by flourishing marine phytoplankton,[14][15]reversal of global warming 49 million years ago by 800,000 years of arctic azolla blooms,[16][17] and global cooling over the past 40 million years driven by the expansion of grass-grazer ecosystems.[18][19] SONY VAIO VGN-AR630E Laptop Keyboard
Slight variations in Earth's orbit lead to changes in the seasonal distribution of sunlight reaching the Earth's surface and how it is distributed across the globe. There is very little change to the area-averaged annually averaged sunshine; but there can be strong changes in the geographical and seasonal distribution. SONY VAIO PCG-FR315M Laptop Keyboard
The three types of orbital variations are variations in Earth's eccentricity, changes in the tilt angle of Earth's axis of rotation, andprecession of Earth's axis. Combined together, DELL Latitude D620 Laptop Keyboard
these produce Milankovitch cycles which have a large impact on climate and are notable for their correlation to glacial and interglacial periods,[20] their correlation with the advance and retreat of the Sahara,[20] and for their appearance in the stratigraphic record.[21] DELL Latitude D620 Laptop Keyboard
The IPCC notes that Milankovitch cycles drove the ice age cycles, CO2 followed temperature change "with a lag of some hundreds of years," and that as a feedback amplified temperature change.[22] SAMSUNG N150 Laptop Keyboard
The depths of the ocean have a lag time in changing temperature (thermal inertia on such scale). Upon seawater temperature change, the solubility of CO2 in the oceans changed, as well as other factors impacting air-sea CO2 exchange.[23] HP Pavilion G6-1B59WM Laptop Keyboard
Solar output
The Sun is the predominant source for energy input to the Earth. Both long- and short-term variations in solar intensity are known to affect global climate.
Three to four billion years ago the sun emitted only 70% as much power as it does today. HP G62-367DX Laptop Keyboard
If the atmospheric composition had been the same as today, liquid water should not have existed on Earth. However, there is evidence for the presence of water on the early Earth, in the Hadean[24][25] DELL V119525BS1 Laptop Keyboard
and Archean[26][24] eons, leading to what is known as the faint young Sun paradox.[27] Hypothesized solutions to this paradox include a vastly different atmosphere, SONY Vaio PCG-K33 Laptop Keyboard
with much higher concentrations of greenhouse gases than currently exist.[28] Over the following approximately 4 billion years, the energy output of the sun increased and atmospheric composition changed. SONY VAIO VGN-N325QE/W Laptop Keyboard
The Great Oxygenation Event – oxygenation of the atmosphere around 2.4 billion years ago – was the most notable alteration. TOSHIBA Satellite A205-S4618 Laptop Keyboard
Over the next five billion years the sun's ultimate death as it becomes a red giant and then a white dwarf will have large effects on climate, with the red giant phase possibly ending any life on Earth that survives until that time. HP G61-424CA laptop keyboard
Solar output also varies on shorter time scales, including the 11-year solar cycle[29] and longer-term modulations.[30]Solar intensity variations are considered to have been influential in triggering the Little Ice Age,[31] Packard Bell Easynote TM81 laptop keyboard
and some of the warming observed from 1900 to 1950. The cyclical nature of the sun's energy output is not yet fully understood; it differs from the very slow change that is happening within the sun as it ages and evolves. HP G61-424CA laptop keyboard
Research indicates that solar variability has had effects including the Maunder minimum from 1645 to 1715 A.D., part of the Little Ice Age from 1550 to 1850 A.D. Compaq Presario CQ56-102SE laptop keyboard
that was marked by relative cooling and greater glacier extent than the centuries before and afterward.[32][33] HP G42-265LA laptop keyboard
Some studies point toward solar radiation increases from cyclical sunspot activity affecting global warming, and climate may be influenced by the sum of all effects (solar variation, anthropogenic radiative forcings, etc.).[34][35] TOSHIBA Satellite A305-S6841 laptop keyboard
Interestingly, a 2010 study[36] suggests, “that the effects of solar variability on temperature throughout the atmosphere may be contrary to current expectations.”
In an Aug 2011 Press Release,[37] HP Mini 210-1081NR laptop keyboard
CERN announced the publication in the Nature journal the initial results from itsCLOUD experiment. The results indicate that ionisation from cosmic rays significantly enhances aerosol formation in the presence of sulphuric acid and water, HP G42-265LA laptop keyboard
but in the lower atmosphere where ammonia is also required, this is insufficient to account for aerosol formation and additional trace vapours must be involved. The next step is to find more about these trace vapours, including whether they are of natural or human origin. TOSHIBA Satellite A305-S6829 laptop keyboard
Volcanic eruptions release gases and particulates into the atmosphere. Eruptions large enough to affect climate occur on average several times per century, and cause cooling (by partially blocking the transmission of solar radiation to the Earth's surface) for a period of a few years. TOSHIBA PK13AT10600 laptop keyboard
The eruption of Mount Pinatubo in 1991, the second largest terrestrial eruption of the 20th century[40] (after the 1912 eruption of Novarupta[41]) affected the climate substantially. Global temperatures decreased by about 0.5 °C (0.9 °F). SONY VGN-FE21B laptop keyboard
The eruption of Mount Tambora in 1815 caused the Year Without a Summer.[42] Much larger eruptions, known as large igneous provinces, occur only a few times every hundred million years, but may cause global warming and mass extinctions.[43] COMPAQ Presario CQ50-210US laptop keyboard
Volcanoes are also part of the extended carbon cycle. Over very long (geological) time periods, they release carbon dioxide from the Earth's crust and mantle, counteracting the uptake by sedimentary rocks and other geological carbon dioxide sinks. DELL V119525BS1 laptop keyboard
The US Geological Survey estimates are that volcanic emissions are at a much lower level than the effects of current human activities, which generate 100–300 times the amount of carbon dioxide emitted by volcanoes.[44] TOSHIBA Satellite C650-182 Laptop Keyboard
A review of published studies indicates that annual volcanic emissions of carbon dioxide, including amounts released from mid-ocean ridges, volcanic arcs, and hot spot volcanoes, are only the equivalent of 3 to 5 days of human caused output. ASUS F3M Laptop Keyboard
The annual amount put out by human activities may be greater than the amount released bysupererruptions, the most recent of which was the Toba eruption in Indonesia 74,000 years ago.[45] Lenovo 63Y0047 Laptop Keyboard
Although volcanoes are technically part of the lithosphere, which itself is part of the climate system, the IPCC explicitly defines volcanism as an external forcing agent.[46]
Plate tectonics HP Pavilion dv6-3107ax Laptop Keyboard
Over the course of millions of years, the motion of tectonic plates reconfigures global land and ocean areas and generates topography. This can affect both global and local patterns of climate and atmosphere-ocean circulation.[47] SONY VAIO VGN-C2S Series Laptop Keyboard
The position of the continents determines the geometry of the oceans and therefore influences patterns of ocean circulation. The locations of the seas are important in controlling the transfer of heat and moisture across the globe, and therefore, in determining global climate. HP 488590-001 Laptop Keyboard
A recent example of tectonic control on ocean circulation is the formation of the Isthmus of Panama about 5 million years ago, which shut off direct mixing between the Atlantic andPacific Oceans. TOSHIBA P000482730 Laptop Keyboard
This strongly affected the ocean dynamics of what is now the Gulf Stream and may have led to Northern Hemisphere ice cover.[48][49] During the Carboniferous period, about 300 to 360 million years ago, plate tectonics may have triggered large-scale storage of carbon and increasedglaciation.[50] SONY 147977821 Laptop Keyboard
Geologic evidence points to a "megamonsoonal" circulation pattern during the time of the supercontinent Pangaea, and climate modeling suggests that the existence of the supercontinent was conducive to the establishment of monsoons.[51] TOSHIBA Tecra M9-S5514 Laptop Keyboard
The size of continents is also important. Because of the stabilizing effect of the oceans on temperature, yearly temperature variations are generally lower in coastal areas than they are inland. A larger supercontinent will therefore have more area in which climate is strongly seasonal than will several smaller continents or islands. GATEWAY NV-54 Laptop Keyboard
Of most concern in these anthropogenic factors is the increase in CO2 levels due to emissions from fossil fuel combustion, followed by aerosols(particulate matter in the atmosphere) and the CO2 released by cement manufacture. FUJITSU Lifebook P1510 Laptop Keyboard
Other factors, including land use, ozone depletion, animal agriculture[54] and deforestation, are also of concern in the roles they play – both sEvidence for climatic change is taken from a variety of sources that can be used to reconstruct past climates. FUJITSU Lifebook P1610 Laptop Keyboard
Reasonably complete global records of surface temperature are available beginning from the mid-late 19th century. DELL Precision M4500 Laptop Keyboard
For earlier periods, most of the evidence is indirect—climatic changes are inferred from changes in proxies, indicators that reflect climate, such as vegetation, ice cores,[55]dendrochronology, sea level change, and glacial geology.
Temperature measurements and proxies HP Pavilion DV7t-3100 laptop keyboard
The instrumental temperature record from surface stations was supplemented by radiosonde balloons, extensive atmospheric monitoring by the mid-20th century, and, from the 1970s on, HP Pavilion dv6-2150es laptop keyboard
withglobal satellite data as well. The 18O/16O ratio in calcite and ice core samples used to deduce ocean temperature in the distant past is an example of a temperature proxy method, as are other climate metrics noted in subsequent categories. HP Pavilion dv6-3107ax laptop keyboard
Historical and archaeological evidence
Main article: Historical impacts of climate change
Climate change in the recent past may be detected by corresponding changes in settlement and agricultural patterns.[56] SONY VAIO VGN-FS415E laptop keyboard
Archaeological evidence, oral history and historical documents can offer insights into past changes in the climate. Climate change effects have been linked to the collapse of various civilizations.[56] HP Pavilion DV7-3165dx laptop keyboard
eparately and in conjunction with other factors – in affecting climate, microclimate, and measures of climate variables.
Glaciers are considered among the most sensitive indicators of climate change.[57] Their size is determined by a mass balance between snow input and melt output. SONY VAIO VGN-NW25GF laptop keyboard
As temperatures warm, glaciers retreat unless snow precipitation increases to make up for the additional melt; the converse is also true.
Glaciers grow and shrink due both to natural variability and external forcings. Compaq Presario CQ71-317EA laptop keyboard
Variability in temperature, precipitation, and englacial and subglacial hydrology can strongly determine the evolution of a glacier in a particular season. Therefore, FUJITSU Lifebook P1610 laptop keyboard
one must average over a decadal or longer time-scale and/or over a many individual glaciers to smooth out the local short-term variability and obtain a glacier history that is related to climate. HP Pavilion dv6-2129ev laptop keyboard
A world glacier inventory has been compiled since the 1970s, initially based mainly on aerial photographs and maps but now relying more on satellites. This compilation tracks more than 100,000 Packard Bell NEW90 laptop keyboard
glaciers covering a total area of approximately 240,000 km2, and preliminary estimates indicate that the remaining ice cover is around 445,000 km2. The World Glacier Monitoring Service collects data annually on glacier retreat and glacier mass balance From this data, SONY VAIO VGN-FS640/W laptop keyboard
glaciers worldwide have been found to be shrinking significantly, with strong glacier retreats in the 1940s, stable or growing conditions during the 1920s and 1970s, and again retreating from the mid-1980s to present.[58] HP 405963-001 laptop keyboard
The most significant climate processes since the middle to late Pliocene (approximately 3 million years ago) are the glacial and interglacial cycles. The present interglacial period (the Holocene) has lasted about 11,700 years.[59] HP Pavilion G6-1223TX Laptop Keyboard
Shaped by orbital variations, responses such as the rise and fall ofcontinental ice sheets and significant sea-level changes helped create the climate. Other changes, including Heinrich events, Dansgaard–Oeschger eventsand the Younger Dryas, HP G42-364LA Laptop Keyboard
however, illustrate how glacial variations may also influence climate without the orbital forcing. SONY VAIO VGN-FS315M Laptop Keyboard
Glaciers leave behind moraines that contain a wealth of material—including organic matter, quartz, and potassium that may be dated—recording the periods in which a glacier advanced and retreated. DELL Vostro PP37L Laptop Keyboard
Similarly, by tephrochronological techniques, the lack of glacier cover can be identified by the presence of soil or volcanic tephra horizons whose date of deposit may also be ascertained. SONY VAIO VGN-C2S Series Laptop Keyboard
The decline in Arctic sea ice, both in extent and thickness, over the last several decades is further evidence for rapid climate change.[60] Sea ice is frozen seawater that floats on the ocean surface. It covers millions of square miles in the polar regions, HP pavilion DV7-1000 Laptop Keyboard
varying with the seasons. In the Arctic, some sea ice remains year after year, whereas almost all Southern Ocean or Antarctic sea ice melts away and reforms annually. Satellite observations show that Arctic sea ice is now HP G42-364LA Laptop Keyboard
A change in the type, distribution and coverage of vegetation may occur given a change in the climate. Some changes in climate may result in increased precipitation and warmth, TOSHIBA 9J.N7482.901 Laptop Keyboard
resulting in improved plant growth and the subsequent sequestration of airborne CO2. A gradual increase in warmth in a region will lead to earlier flowering and fruiting times, driving a change in the timing of life cycles of dependent organisms. Conversely, TOSHIBA Satellite U305-S2804 Laptop Keyboard
cold will cause plant bio-cycles to lag.[62] Larger, faster or more radical changes, however, may result in vegetation stress, rapid plant loss and desertification in certain circumstances.[63][64] HP 597635-001 Laptop Keyboard
An example of this occurred during the Carboniferous Rainforest Collapse (CRC), an extinction event 300 million years ago. At this time vast rainforests covered the equatorial region of Europe and America. Compaq Presario CQ57 Series Laptop Keyboard
Climate change devastated these tropical rainforests, abruptly fragmenting the habitat into isolated 'islands' and causing the extinction of many plant and animal species.[63] DELL Vostro 1014 Laptop Keyboard
Satellite data available in recent decades indicates that global terrestrial net primary production increased by 6% from 1982 to 1999, with the largest portion of that increase in tropical ecosystems, then decreased by 1% from 2000 to 2009.[65][66]
Pollen analysisLenovo 3000 N200 Laptop Keyboard
Palynology is the study of contemporary and fossil palynomorphs, including pollen. Palynology is used to infer the geographical distribution of plant species, which vary under different climate conditions. HP Pavilion zv6223ea Laptop Keyboard
Different groups of plants have pollen with distinctive shapes and surface textures, and since the outer surface of pollen is composed of a very resilient material, they resist decay. Changes in the type of pollen found in different layers of sediment in lakes, bogs, or river deltas indicate changes in plant communities. These changes are often a sign of a changing climate. Lenovo Thinkpad T520 Laptop Keyboard
As an example, palynological studies have been used to track changing vegetation patterns throughout the Quaternary glaciations[69] and especially since the last glacial maximum.[70] ACER Aspire 4736Z laptop keyboard
Past precipitation can be estimated in the modern era with the global network of precipitation gauges. Surface coverage over oceans and remote areas is relatively sparse, but, reducing reliance on interpolation, satellite data has been available since the 1970s.[72] TOSHIBA Satellite L755-S5216 laptop keyboard
Quantification of climatological variation of precipitation in prior centuries and epochs is less complete but approximated using proxies such as marine sediments, ice cores, cave stalagmites, and tree rings.[73] HP Pavilion DV6z artist edition 2 laptop keyboard
Climatological temperatures substantially affect precipitation. For instance, during the Last Glacial Maximum of 18,000 years ago, thermal-driven evaporation from the oceans onto continental landmasses was low, HP Pavilion dv6-3142se laptop keyboard
causing large areas of extreme desert, including polar deserts (cold but with low rates of precipitation).[71] In contrast, the world's climate was wetter than today near the start of the warm Atlantic Period of 8000 years ago.[71] TOSHIBA Satellite P300-ST3712 laptop keyboard
Estimated global land precipitation increased by approximately 2% over the course of the 20th century, though the calculated trend varies if different time endpoints are chosen, HP G42-265LA laptop keyboard
complicated by ENSO and other oscillations, including greater global land precipitation in the 1950s and 1970s than the later 1980s and 1990s despite the positive trend over the century overall.[72][74][75] Similar slight overall increase in global river runoff and in average soil moisture has been perceived.[74] SONY VAIO VGN-FS620 laptop keyboard
Dendroclimatology
Dendroclimatology is the analysis of tree ring growth patterns to determine past climate variations.[76] Wide and thick rings indicate a fertile, well-watered growing period, whilst thin, narrow rings indicate a time of lower rainfall and less-than-ideal growing conditions. HP Pavilion dv3-2155mx laptop keyboard
Ice cores
Analysis of ice in a core drilled from an ice sheet such as the Antarctic ice sheet, can be used to show a link between temperature and global sea level variations. The air trapped in bubbles in the ice can also reveal the CO2 variations of the atmosphere from the distant past, TOSHIBA PK130BH2A00 laptop keyboard
well before modern environmental influences. The study of these ice cores has been a significant indicator of the changes in CO2 over many millennia, and continues to provide valuable information about the differences between ancient and modern atmospheric conditions. SONY VAIO VGN-CR123E laptop keyboard
Animals
Remains of beetles are common in freshwater and land sediments. Different species of beetles tend to be found under different climatic conditions. Given the extensive lineage of beetles whose genetic makeup has not altered significantly over the millennia, Lenovo ThinkPad T510-4339 laptop keyboard
knowledge of the present climatic range of the different species, and the age of the sediments in which remains are found, past climatic conditions may be inferred.[77] HP Pavilion dv6-2130ca laptop keyboard
Similarly, the historical abundance of various fish species has been found to have a substantial relationship with observed climatic conditions.[78]Changes in the primary productivity of autotrophs in the oceans can affect marine food webs.[79] Packard Bell Easynote TK85 laptop keyboard
Sea level change
Main articles: Sea level and Current sea level rise
Global sea level change for much of the last century has generally been estimated using tide gauge measurements collated over long periods of time to give a long-term average. DELL Inspiron 1750 Laptop Keyboard
More recently, altimeter measurements — in combination with accurately determined satellite orbits — have provided an improved measurement of global sea level change.[80] HP Pavilion DV6z artist edition 2 Laptop Keyboard
To measure sea levels prior to instrumental measurements, scientists have dated coral reefs that grow near the surface of the ocean, coastal sediments, marine terraces, ooids in limestones, DELL Vostro 3550 Laptop Keyboard
and nearshore archaeological remains. The predominant dating methods used are uranium series and radiocarbon, with cosmogenic radionuclides being sometimes used to date terraces that have experienced relative sea level fall. HP Pavilion dv6-2125ef laptop keyboard
In the early Pliocene, global temperatures were 1–2˚C warmer than the present temperature, yet sea level was 15–25 meters higher than today.[81] HP Pavilion dv6-2110ev laptop keyboard
Rhododendron is the national flower of himalayan republic of Nepal. Rhododendron is a genus characterized by shrubs and small to (rarely) large trees, the smallest species growing to 10–100 cm (3.9–39 in) tall, and the largest, R. protistum var. giganteum, reported to 30 m (98 ft) tall.[4][5] SONY VAIO VGN-N31Z/W laptop keyboard
The leaves are spirally arranged; leaf size can range from 1–2 cm (0.39–0.79 in) to over 50 cm (20 in), exceptionally 100 cm (39 in) in R. sinogrande. They may be either evergreen or deciduous. ACER TravelMate 6252 laptop keyboard
In some species, the undersides of the leaves are covered with scales (lepidote) or hairs (indumentum). Some of the best known species are noted for their many clusters of large flowers. SONY VGN-FE11M laptop keyboard
There are alpine species with small flowers and small leaves, and tropical species such as section Vireya that often grow as epiphytes. Species in this genus may be part of the heath complex in oak-heath forests in eastern North America.[6][7] TOSHIBA Satellite L750-ST4NX1 laptop keyboard
Both species and hybrid rhododendrons (including azaleas) are used extensively as ornamental plants in landscaping in many parts of the world, and many species and cultivars are grown commercially for the nursery trade. Rhododendrons are often valued in landscaping for their structure, size, ASUS X53S laptop keyboard
flowers, and the fact that many of them are evergreen.[12]Azaleas are frequently used around foundations and occasionally as hedges, and many larger-leafed rhododendrons lend themselves well to more informal plantings and woodland gardens, Acer eMachines E640 laptop keyboard
or as specimen plants. In some areas, larger rhododendrons can be pruned to encourage more tree-like form, with some species such as R. arboreum and R. falconerieventually growing to 10–15 m or more tall.[12] TOSHIBA Satellite L655-S5107 laptop keyboard
Like other ericaceous plants, most rhododendrons prefer acid soils with a pH of roughly 4.5-5.5; some tropical Vireyas and a few other rhododendron species grow as epiphytes and require a planting mix similar to orchids. Rhododendrons have fibrous roots and prefer well-drained soils high in organic material. HP Pavilion DV6z artist edition 2 laptop keyboard
In areas with poorly drained or alkaline soils, rhododendrons are often grown in raised beds using media such as composted pine bark.[24] Mulching and careful watering are important, especially before the plant is established. SONY VAIO VGN-N250E/B laptop keyboard
A new calcium-tolerant stock of rhododendrons (patented as 'Inkarho') has been exhibited at the RHS Chelsea Flower Showin London (2011). SONY Vaio PCG-K315S laptop keyboard
Individual hybrids of rhododendrons have been grafted on to a rootstock on a single rhododendron plant that was found growing in a chalk quarry. The rootstock is able to grow in calcium-rich soil up to a pH of 7.5.[25][26] HP Pavilion DV7-3067nr laptop keyboard
Some species of rhododendron are poisonous to grazing animals because of a toxin called grayanotoxin in their pollen and nectar. People have been known to become ill from eating honey made by bees feeding on rhododendron and azalea flowers. HP G42-380LA Laptop Keyboard
Xenophon described the odd behavior of Greek soldiers after having consumed honey in a village surrounded by Rhododendron ponticum during the march of the Ten Thousand in 401 BC. GATEWAY NV-53 Laptop Keyboard
Pompey's soldiers reportedly suffered lethal casualties following the consumption of honey made from Rhododendron deliberately left behind by Pontic forces in 67 BC during the Third Mithridatic War. HP 646568-001 Laptop Keyboard
Later, it was recognized that honey resulting from these plants has a slightly hallucinogenic and laxative effect.[27] The suspect rhododendrons are Rhododendron ponticum and Rhododendron luteum (formerly Azalea pontica), ACER Aspire One D150-1920 Laptop Keyboard
both found in northern Asia Minor. Eleven similar cases have been documented in Istanbul, Turkey during the 1980s.[28] Rhododendron is extremely toxic to horses, with some animals dying within a few hours of ingesting the plant, although most horses tend to avoid it if they have access to good forage. HP AEUT5U00010 Laptop Keyboard
The effects of R. ponticum was mentioned in the 2009 filmSherlock Holmes as a proposed way to arrange a fake execution.[29] It was also mentioned in the third episode of Season 2 of BBC's Sherlock (TV series), and has been speculated to have been a part of Sherlock's fake death scheme. ACER Aspire One D150-1920 Laptop Keyboard
Rhododendrons are grown commercially in many areas for sale, and are occasionally collected in the wild, a practice now rare in most areas. Larger commercial growers often ship long distances; in the United States, HP AEUT5U00010 Laptop Keyboard
most of them are located on the west coast (Oregon, Washington state and California). Large-scale commercial growing often selects for different characteristics that hobbyist growers might want, APPLE A1278 Laptop Keyboard
such as resistance to root rot when overwatered, ability to be forced into budding early, ease of rooting or other propagation, and saleability.[13] ACER 9J.N0F82.A1D Laptop Keyboard
In the Indian state of Himachal Pradesh, rhododendron flowers have been used for some time to make popular fruit and flower wines. The industry is promoted by the state government with tax benefits, looking to promote this industry as a full-fledged subclass of its economy.[14] HP G72-b66US Laptop Keyboard
Rhododendron arboreum (lali guransh) is the national flower of Nepal. R. ponticum is the state flower of Indian-administered Kashmir and Pakistan-controlled Kashmir. Rhododendron niveum is the state tree of Sikkim in India. ACER 9J.N0F82.A1D Laptop Keyboard
Rhododendron is also the state tree of the state of Uttarakhand, India. Themountain laurel (Kalmia latifolia) is the state flower of the state of Pennsylvania, in the United States. HP G72-b66US Laptop Keyboard
Rhododendron maximum, the most widespread rhododendron of the Appalachian Mountains, is the state flower of West Virginia, and is in the Flag of West Virginia. Rhododendron macrophyllum, a widespread rhododendron of the Pacific Northwest, is the state flower of Washington. HP Mini 110-3180sv Laptop Keyboard
The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters. Lenovo 3000 N200 Laptop Keyboard
It was formed by the fusion of Indian and Australian plates 43 million years ago.[1] Recent studies, and seismic events such as the 2012 Indian Ocean earthquake, DELL Vostro 3450 Laptop Keyboard
suggest that the Indo-Australian Plate may be in the process of breaking up into two separate plates due primarily to stresses induced by the collision of the Indo-Australian Plate with Eurasia along the Himalayas.[2] HP G72-b60SF laptop keyboard
The eastern part (Australia) is moving northward at the rate of 5.6 cm per year while the western part (India) is moving only at the rate of 3.7 cm per year due to impediment by Himalayas. HP Mini 110-3180sv laptop keyboard
This differential movement is resulting in the compression of the plate near its center at Sumatra and a potential division into Indian and Australian Plates.[3][4][5] The two protoplates or subplates are generally referred to as the Indian Plate and the Australian Plate. LENOVO IdeaPad S10 20015 laptop keyboard
A third Capricorn Plate may also be separating off of the west side of the Indian subplate.[6]
The Indian subcontinent, Meganesia (Australia, New Guinea, and Tasmania), New Zealand, HP Mini 110-3180sv laptop keyboard
and New Caledonia are all fragments of the ancient supercontinent of Gondwana. Seafloor spreading separated these land masses from one another, but as the spreading centers became inactive the land masses fused into a single plate. Lenovo ThinkPad Edge E125 laptop keyboard
Recent GPS measurement in Australia confirms the plate’s velocity of 67 mm/yr at 35 degrees east of north . Note also the same directions and velocities for points at Auckland, Christmas Island and southern India. HP Pavilion dv6-3230us laptop keyboard
A slight difference in local direction at Auckland is presumed due to a slight buckling of the plate there, where it is being compressed by the Pacific Plate. DELL Inspiron 6400 Laptop Keyboard
The northeasterly side is a complex but generally convergent boundary with the Pacific Plate. The Pacific Plate is subducting under the Australian Plate, ACER K052030A1 laptop keyboard
which forms the Tonga and Kermadec Trenches, and the parallel Tonga and Kermadec island arcs. It has also uplifted the eastern parts of New Zealand'sNorth Island.
The continent of Zealandia, TOSHIBA NSK-TAJ01 Laptop Keyboard
which separated from Australia 85 million years ago and stretches from New Caledonia in the north to New Zealand’s subantarctic islands in the south, is now being torn apart along the transform boundary marked by the Alpine Fault. ACER Aspire 7741G Laptop Keyboard
South of New Zealand the boundary becomes a transitional transform-convergent boundary, the Macquarie Fault Zone, where the Australian Plate is beginning to subduct under the Pacific Plate along the Puysegur Trench. Extending southwest of this trench is the Macquarie Ridge. ACER Aspire 7741G Laptop Keyboard
The southerly side is a divergent boundary with the Antarctic Plate called the Southeast Indian Ridge (SEIR). The westerly side is a transform boundary with the Arabian Plate called the Owen Fracture Zone, and a divergent boundary with the African Plate called the Central Indian Ridge (CIR). SONY KFRMBA152B Laptop Keyboard
The northerly side of the Indo-Australian Plate is a convergent boundary with the Eurasian Plate forming the Himalaya and Hindu Kush mountains. HP Pavilion dv6-3001so Laptop Keyboard
The northwest side of the Indo-Australian plate forms a subducting boundary with the Eurasian plate on the borders of the Indian Ocean from Bangladesh, toMyanmar to the south-west of Indonesian islands of Sumatra and Java. HP HDX18-1100 CTO Laptop Keyboard
The subducting boundary through Indonesia is not parallel to the biogeographical Wallace line that separates the indigenous fauna of Asia from that ofAustralasia. The Eastern islands of Indonesia lie mainly on the Eurasian Plate, but have Australasian-related fauna and flora. Southeasterly lies theSunda Shelf. TOSHIBA Satellite C655-S9521D Laptop Keyboard
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which forms thecontinents and the areas of shallow seabed close to their shores, known as continental shelves. HP Pavilion dv6-2160ep laptop keyboard
This layer is sometimes called sial because there is more felsic, or granitic, bulk composition, which lies in contrast to the oceanic crust, called sima because of the mafic or basaltic rock. (Based on the change in velocity of seismic waves, Packard Bell PEW91 laptop keyboard
it is believed that at a certain depth sial becomes close in its physical properties to sima. This line is called the Conrad discontinuity.)
Consisting mostly of granitic rock, continental crust has a density of about 2.7 g/cm3 and is lessdense than the material of the Earth's mantle (density of about 3.3 g/cm3), HP Pavilion dv6-2159tx laptop keyboard
which consists of mafic rock. Continental crust is also less dense than oceanic crust (density of about 2.9 g/cm3), though it is considerably thicker; mostly 25 to 70 km versus the average oceanic thickness of around 7–10 km. DELL 0M711P laptop keyboard
About 40% of the Earth's surface is now overlaid by continental crust.[1] Continental crust makes up about 70% of the volume of Earth's crust.[2] SONY VAIO VGN-CR13/B laptop keyboard
In contrast to the persistence of continental crust, the size, shape, and number of continents are constantly changing through geologic time. Different tracts rift apart, collide and recoalesce as part of a grand supercontinent cycle.[4] There are currently about 7 billion cubic kilometers of continental crust, SONY 148701322 laptop keyboard
but this quantity varies because of the nature of the forces involved. The relative permanence of continental crust contrasts Packard Bell Easynote TK85 laptop keyboard
active margins of the two meet in subduction zones, the oceanic crust is typically subducted back into the mantle. Continental crust is rarely subducted (this may occur where continental crustal blocks collide and overthicken, HP Pavilion dv6-3001so laptop keyboard
causing deep melting under mountain belts such as the Himalayas or the Alps). For this reason the oldest rocks on Earth are within thecratons or cores of the continents, rather than in repeatedly recycled oceanic crust; the oldest intact crustal fragment is the Acasta Gneiss at 4.01 Ga, HP HDX18-1100 CTO laptop keyboard
while the oldest oceanic crust (located on the Pacific Plate offshore of Kamchatka) is no older than Jurassic (~180 Ma). Continental crust and the rock layers that lie on and within it are thus the best archive of Earth history.[1][5] SONY VAIO VGN-N21E/W laptop keyboard
The height of mountain ranges is usually related to the thickness of crust. This results from the isostasy associated with orogeny (mountain formation). The crust is thickened by the compressive forces related to subduction or continental collision. HP Pavilion dv5-1118tx laptop keyboard
The buoyancy of the crust forces it upwards, the forces of the collisional stress balanced by gravity and erosion. This forms a keel or mountain root beneath the mountain range, which is where the thickest crust is found.[6] The thinnest continental crust is found in rift zones, HP AEUT5U00010 laptop keyboard
where the crust is thinned by detachment faulting and eventually severed, replaced by oceanic crust. The edges of continental fragments formed this way (both sides of the Atlantic Ocean, for example) are termed passive margins. HP Mini 110-3504tu laptop keyboard
The high temperatures and pressures at depth, often combined with a long history of complex distortion, cause much of the lower continental crust to be metamorphic - the main exception to this being recent igneous intrusions. SONY VGN-FE21H laptop keyboard
Igneous rock may also be "underplated" to the underside of the crust, i.e. adding to the crust by forming a layer immediately beneath it.
Continental crust is produced and (far less often) destroyed mostly by plate tectonic processes, especially at convergent plate boundaries. TOSHIBA Satellite U305-S2812 Laptop Keyboard
Additionally, continental crustal material is transferred to oceanic crust by sedimentation. New material can be added to the continents by the partial melting of oceanic crust at subduction zones, causing the lighter material to rise as magma, forming volcanoes. GATEWAY M-6319 Laptop Keyboard
Also, material can be accreted horizontally when volcanic island arcs, seamounts or similar structures collide with the side of the continent as a result of plate tectonic movements. HP 634139-001 Laptop Keyboard
Continental crust is also lost through erosion and sediment subduction, tectonic erosion of forearcs, delamination, and deep subduction of continental crust in collision zones.[7] TOSHIBA Satellite L655-S5083 Laptop Keyboard
Many theories of crustal growth are controversial, including rates of crustal growth and recycling, whether the lower crust is recycled differently than the upper crust and over how much of Earth history plate tectonics has operated and so could be the dominant mode of continental crust formation and destruction.[8] ACER Aspire 5742 Laptop Keyboard
It is a matter of debate whether the amount of continental crust has been increasing, decreasing, or remaining constant over geological time. One model indicates that at prior to 3.7 Ga ago continental crust constituted less than 10% of the present amount.[9] HP pavilion DV7-1000 Laptop Keyboard
By 3.0 Ga ago the amount was about 25%, and following a period of rapid crustal evolution it was about 60% of the current amount by 2.6 Ga ago.[10] The growth of continental crust appears to have occurred in spurts of increased activity corresponding to five episodes of increased production through geologic time.[11] TOSHIBA Satellite A300 Laptop Keyboard
The Tibetan Plateau (Tibetan: བོད་ས་མཐོ།, Wylie: bod sa mtho), also known in China as theQinghai-Tibet (Qingzang) Plateau (Chinese: pinyin: Qīngzàng Gāoyuán) orHimalayan Plateau is a vast, elevated plateau in Central Asia[1][2][3][4] or East Asia[5][6][7][8] TOSHIBA Satellite A110 Series Laptop Keyboard
covering most of the Tibet Autonomous Region and Qinghai Province in western China, as well as part of Ladakh in Jammu and Kashmir state of India. It stretches approximately 1,000 kilometres (620 mi) SONY VGN-FE670G Laptop Keyboard
north to south and 2,500 kilometres (1,600 mi) east to west. With an average elevation exceeding 4,500 metres (14,800 ft), the Tibetan Plateau is sometimes called "the Roof of the World" and is the world's highest and largest plateau, HP COMPAQ NX6310 Laptop Keyboard
with an area of 2,500,000 square kilometres (970,000 sq mi) (about four times the size of France).[9] Sometimes termed the "Third Pole", the Tibetan Plateau is the headwaters of thedrainage basins of most of the streams in surrounding regions. DELL INSPIRON 1464 Laptop Keyboard
Its tens of thousands ofglaciers and other geographical and ecological features serve as a "water tower" storing water and maintaining flow. The impact of global warming on the Tibetan Plateau is of intense scientific interest.[10] SONY Vaio PCG-K315S laptop keyboard
The Tibetan Plateau is bounded on the north by a broad escarpment where the altitude drops from around 5,000 metres (16,000 ft) to 1,500 metres (4,900 ft) in less than 150 kilometres (93 mi). Along the escarpment is a range of mountains. TOSHIBA Satellite C655-S5141 laptop keyboard
In the west the Kunlun Mountains separate the plateau from the Tarim Basin. About half way across the Tarim the bounding range becomes the Altyn-Tagh and the Kunluns, by convention, HP Mini 110-3504tu laptop keyboard
continu B e somewhat to the south. In the 'V' formed by this split is the western part of the Qaidamasin. The Altyn-Tagh ends near the Dangjin pass on theDunhuang-Golmud road. Lenovo Thinkpad T520 Laptop Keyboard
To the west are short ranges called the Danghe, Yema, Shule and Tulai Nanshans. The easternmost range is the Qilian Mountains. The line of mountains continues east of the plateau as the Qin Mountains which separate the Ordos Region from Sichuan. SONY VGN-FE11H Laptop Keyboard
North of the mountains runs the Gansu or Hexi Corridor which was the main silk-road route from China proper to the west. COMPAQ Presario C700 Laptop Keyboard
The plateau is a high-altitude arid steppe interspersed with mountain ranges and large brackish lakes. Annual precipitation ranges from 100 to 300 millimetres (3.9 to 12 in) and falls mainly as hailstorms. Lenovo 45N2240 Laptop Keyboard
The southern and eastern edges of the steppe have grasslands which can sustainably support populations of nomadic herdsmen, although frost occurs for six months of the year. SONY VGN-FE550G Laptop Keyboard
Permafrost occurs over extensive parts of the plateau. Proceeding to the north and northwest, the plateau becomes progressively higher, colder and drier, until reaching the remote Changthang region in the northwestern part of the plateau. Lenovo IdeaPad Y710 Laptop Keyboard
Here the average altitude exceeds 5,000 metres (16,000 ft) and winter temperatures can drop to −40 °C (−40 °F). As a result of this extremely inhospitable environment, the Changthang region (together with the adjoining Kekexili region) is the least populous region in Asia, DELL Latitude D830 Laptop Keyboard
and the third least populous area in the world afterAntarctica and northern Greenland.
The Himalayas are among the youngest mountain ranges on the planet and consist mostly of uplifted sedimentary andmetamorphic rock. TOSHIBA Satellite U305-S2812 Laptop Keyboard
According to the modern theory of plate tectonics, their formation is a result of a continental collision or orogeny along the convergent boundary between the Indo-Australian Plate and the Eurasian Plate. They are referred to as fold mountains. GATEWAY M-6319 Laptop Keyboard
The collision began in the Upper Cretaceous period about 70 million years ago, when the north-moving Indo-Australian Plate, moving at about 15 cm per year, collided with the Eurasian Plate. HP 634139-001 Laptop Keyboard
About 50 million years ago, this fast moving Indo-Australian plate had completely closed the Tethys Ocean, the existence of which has been determined by sedimentary rocks settled on the ocean floor, TOSHIBA Satellite L655-S5083 Laptop Keyboard
and the volcanoes that fringed its edges. Since these sediments were light, they crumpled into mountain ranges rather than sinking to the floor. The Indo-Australian plate continues to be driven horizontally below the Tibetan plateau, which forces the plateau to move upwards, the plateau is still rising about 5 mm per year. ACER Aspire 5742 Laptop Keyboard
Monsoons are caused by the larger amplitude of the seasonal cycle of land temperature compared to that of nearby oceans. This differential warming happens because heat in the ocean is mixed vertically through a "mixed layer" that may be fifty meters deep, HP pavilion DV7-1000 Laptop Keyboard
through the action of wind and buoyancy-generated turbulence, whereas the land surface conducts heat slowly, with the seasonal signal penetrating perhaps a meter or so. Additionally, the specific heat capacity of liquid water is significantly higher than that of most materials that make up land. TOSHIBA Satellite A300 Laptop Keyboard
Together, these factors mean that the heat capacity of the layer participating in the seasonal cycle is much larger over the oceans than over land, with the consequence that the air over the land warms faster and reaches a higher temperature than the air over the ocean.[15] IBM ThinkPad T42 laptop keyboard
The hot air over the land tends to rise, creating an area of low pressure. This creates a steady wind blowing toward the land, bringing the moist near-surface air over the oceans with it. Similar rainfall is caused by the moist ocean air being lifted upwards by mountains, surface heating, DELL Inspiron N4050 laptop keyboard
convergence at the surface, divergence aloft, or from storm-produced outflows at the surface. However the lifting occurs, the air cools due expansion in lower pressure, which in turn produces condensation. GATEWAY MT3707 laptop keyboard
In winter, the land cools off quickly, but the ocean keeps the heat longer. The hot air over the ocean rises, creating a low pressure area and a breeze from land to ocean while a large area of drying high pressure is formed over the land, increased by wintertime cooling.[15] HP Pavilion dv6-3050tx laptop keyboard
Monsoons are similar to sea and land breezes, a term usually referring to the localized, diurnal (daily) cycle of circulation near coastlines everywhere, but they are much larger in scale, stronger and seasonal.[16] SONY VGN-FE48E laptop keyboard
The seasonal monsoon wind shift and weather associated with the heating and cooling of the Tibetan plateau is the strongest such monsoon on Earth.
Today, Tibet is an important heating surface of the atmosphere. Lenovo Thinkpad T520 laptop keyboard
However, during the Last Ice Age a c. 2,400,000 square kilometres (930,000 sq mi) ice sheet covered the plateau.[17][18][19] Due to its great extent, this glaciation in the subtropics was an important element of climate forcing. Compaq Presario CQ71-403SA laptop keyboard
With a much lower latitude, the ice in Tibet reflected at least 4 times more radiation energy per unit area into space than ice at higher latitudes. Thus, what at present adds heat to the atmosphere subtracted it instead.[20]
This cooling had multiple effects on regional climate. HP Pavilion dv6-2150us laptop keyboard
This lack of monsoon caused extensive rainfall over the Sahara desert, expansion of the Thar desert, more dust deposited into the Arabian Sea, and a lowering of the biotic life zones on the Indian subcontinent. Animals responded to this shift in climate, with the Javan Rusa deer migrating into India.[21] HP Pavilion dv6-2030ev laptop keyboard
In addition, the glaciers in Tibet created meltwater lakes in the Qaidam Basin, the Tarim Basin and the Gobi Desert, despite the strong evaporation caused by the low latitude. Silt and clay from the glaciers accumulated in these lakes: when the lakes dried at the end of the ice age, TOSHIBA Satellite L655-S5083 laptop keyboard
the silt and clay were blown by the downslope wind off the Plateau. These airborne fine grains produced the enormous amount of loess in the Chinese lowlands.[21]
Since the end of the ice age, TOSHIBA Satellite L655-S5160 laptop keyboard
Tibet has risen at approximately 10 millimetres (0.39 in) per year, at the same rate as the Himalaya. While the Himalaya rise can be explained by plate tectonics, Lenovo 3000 G430 4152 laptop keyboard
the rise of Tibet can be explained as the isostatic rebound of the crust rising after the weight of the ice was removed. The amount of isostatic rebound since the last ice age is approximately 650 metres (2,130 ft).[19] Packard Bell Easynote TK85 laptop keyboard
The Tibetan Plateau contains the world's third-largest store of ice. Qin Dahe, the former head of the China Meteorological Administration, said that the recent fast pace of melting and warmer temperatures will be good for agriculture and tourism in the short term; but issued a strong warning: Acer eMachines E640 laptop keyboard
"Temperatures are rising four times faster than elsewhere in China, and the Tibetan glaciers are retreating at a higher speed than in any other part of the world." "In the short term, TOSHIBA Satellite L200 laptop keyboard
this will cause lakes to expand and bring floods and mudflows." "In the long run, the glaciers are vital lifelines for Asian rivers, including the Indus and the Ganges. Once they vanish, water supplies in those regions will be in peril."[22] TOSHIBA NSK-TK001 laptop keyboard
HP Mini 1010LA laptop keyboard
TOSHIBA Satellite L505-S5993 laptop keyboard
The Himalayas, also Himalaya, (/ˌhɪməˈleɪ.ə/ or /hɪˈmɑːləjə/; Sanskrit, hima (snow) + ālaya (dwelling), literally, "abode of the snow"[1]) is a mountain range in Asia separating the plains of the Indian subcontinent from the Tibetan Plateau. ACER Travelmate 4152nlci Laptop CPU Cooling Fan
The Himalayan range is home to the planet's highest peaks, including the highest, Mount Everest. The Himalayas include over a hundred mountains exceeding 7,200 metres (23,600 ft) in height. HP pavilion DV7-1000 Laptop Keyboard
By contrast, the highest peak outside Asia—Aconcagua, in the Andes— is 6,961 metres (22,838 ft) tall.[2] The Himalayas have profoundly shaped the cultures of South Asia. Many Himalayan peaks are sacred in both Buddhism and Hinduism. HP Mini 110-1120LA Laptop Keyboard
Besides the Greater Himalayas of these high peaks there are parallel lower ranges. The first foothills, reaching about a thousand meters along the northern edge of the plains, ACER Aspire 5742 Laptop Keyboard
are called the Sivalik Hills or Sub-Himalayan Range. Further north is a higher range reaching two to three thousand meters known as the Lower Himalayan or Mahabharat Range. ACER TravelMate 4100 Laptop Keyboard
The Himalayas abut or cross five countries: Bhutan, India, Nepal, China, and Pakistan, with the first three countries having sovereignty over most of the range.[3] The Himalayas are bordered on the northwest by theKarakoram and Hindu Kush ranges, HP Envy 15 Laptop Keyboard
on the north by the Tibetan Plateau, and on the south by the Indo-Gangetic Plain.
Three of the world's major rivers, the Indus, the Ganges, and the Tsangpo-Brahmaputra all rise near Mount Kailash to cross and encircle the Himalayas. Their combined drainage basin is home to some 600 million people. DELL Vostro 3550 Laptop Keyboard
Lifted by the collision of the Indian tectonic plate with the Eurasian Plate,[4] the Himalayan range runs, west-northwest to east-southeast, in an arc 2,400 kilometres (1,500 mi) long. Its western anchor, ACER Aspire 5810T-8929 Laptop Keyboard
Nanga Parbat, lies just south of the northernmost bend of Indus river, its eastern anchor, Namcha Barwa, just west of the great bend of the Tsangpo river. The range varies in width from 400 kilometres (250 mi) in the west to 150 kilometres (93 mi) in the east. Compaq Presario CQ42-228LA Laptop Keyboard
The flora and fauna of the Himalayas vary with climate, rainfall, altitude, and soils. The climate ranges from tropical at the base of the mountains to permanent ice and snow at the highest elevations. HP Pavilion DV7-3065dx Laptop Keyboard
Owing to the mountains’ latitude near the Tropic of Cancer, the permanent snow line is among the highest in the world at typically around 5,500 metres (18,000 ft).[5] In contrast, DELL E141395 Laptop Keyboard
equatorial mountains in New Guinea, theRwenzoris and Colombia have a snow line some 900 metres (2,950 ft) lower.[6] The amount of yearly rainfall increases from west to east along the southern front of the range. ACER Aspire 7745G Laptop Keyboard
This diversity of altitude, rainfall and soil conditions combined with the very high snow line supports a variety of distinct plant and animal communities. For example the extremes of high altitude (low atmospheric pressure) combined with extreme cold allow extremophile organisms to survive.[7]
The unique floral and faunal wealth of the Himalayas iCompaq Presario CQ42-228LA Laptop Keyboard
s undergoing structural and compositional changes due to climate change. The increase in temperature may shift various species to higher elevations. The oak forest is being invaded by pine forests in the Garhwal Himalayan region. HP G72-c55DX Laptop Keyboard
There are reports of early flowering and fruiting in some tree species, especially rhododendron, apple and Myrica esculenta. The highest known tree species in the Himalayas isJuniperus tibetica located at 4,900 metres (16,080 ft) in Southeastern Tibet.[8] Lenovo 3000 Y510a 15303 laptop keyboard
The Himalaya are among the youngest mountain ranges on the planet and consist mostly of uplifted sedimentary andmetamorphic rock. According to the modern theory of plate tectonics, HP Pavilion dv6-2030ev laptop keyboard
their formation is a result of a continental collision or orogeny along the convergent boundary between the Indo-Australian Plate and the Eurasian Plate. The Arakan Yoma highlands in Myanmar and the Andaman and Nicobar Islands in the Bay of Bengal were also formed as a result of this collision. DELL Inspiron N4050 laptop keyboard
During the Upper Cretaceous, about 70 million years ago, the north-moving Indo-Australian Plate was moving at about 15 cm per year. About 50 million years ago, this fast moving Indo-Australian plate had completely closed the Tethys Ocean, HP Pavilion dv6-2060ea laptop keyboard
the existence of which has been determined by sedimentary rocks settled on the ocean floor, and the volcanoesthat fringed its edges. Since both plates were composed of low density continental crust, HP Pavilion dv6-2155ee laptop keyboard
they were thrust faulted andfolded into mountain ranges rather than subducting into the mantle along an oceanic trench.[4] An often-cited fact used to illustrate this process is that the summit of Mount Everest is made of marine limestone from this ancient ocean.[9] DELL Latitude E5410 laptop keyboard
Today, the Indo-Australian plate continues to be driven horizontally below the Tibetan plateau, which forces the plateau to continue to move upwards. The Indo-Australian plate is still moving at 67 mm per year, ACER TravelMate 3020 laptop keyboard
and over the next 10 million years it will travel about 1,500 km into Asia. About 20 mm per year of the India-Asia convergence is absorbed by thrusting along the Himalaya southern front. This leads to the Himalayas rising by about 5 mm per year, making them geologically active. ACER TravelMate 2403 Series laptop keyboard
The movement of the Indian plate into the Asian plate also makes this region seismically active, leading to earthquakes from time to time. HP pavilion DV7-1029eg laptop keyboard
During the last ice age, there was a connected ice stream of glaciers between Kangchenjunga in the east and Nanga Parbat in the west.[10] In the west, the glaciers joined with the ice stream network in the Karakoram, and in the north, joined with the former Tibetan inland ice. SONY VAIO VGN-AW25GJ laptop keyboard
To the south, outflow glaciers came to an end below an elevation of 1,000–2,000 metres (3,300–6,600 ft).[10][11] While the current valley glaciers of the Himalaya reach at most 20 to 32 kilometres (12 to 20 mi) in length, several of the main valley glaciers were 60 to 112 kilometres (37 to 70 mi) long during the ice age.[10] SONY VAIO PCG-F50/BP laptop keyboard
The glacier snowline (the altitude where accumulation and ablation of a glacier are balanced) was about 1,400–1,660 metres (4,600–5,450 ft) lower than it is today. Thus, the climate was at least 7.0 to 8.3 °C (13 to 15 °F change) colder than it is today.[12] DELL Inspiron 1750 Laptop Keyboard
The easternmost Himalayan rivers feed the Ayeyarwady River, which originates in eastern Tibet and flows south throughMyanmar to drain into the Andaman Sea.
The Salween, Mekong, HP 448159-001 Laptop Keyboard
Yangtze and Huang He (Yellow River) all originate from parts of the Tibetan plateau that are geologically distinct from the Himalaya mountains, and are therefore not considered true Himalayan rivers. DELL Latitude E6500 Laptop Keyboard
Some geologists refer to all the rivers collectively as the circum-Himalayan rivers.[14] In recent years, scientists have monitored a notable increase in the rate of glacier retreat across the region as a result of global climate change.[15] DELL Studio 1737 Laptop Keyboard
For example, Glacial lakes have been forming rapidly on the surface of the debris-covered glaciers in the Bhutan Himalaya during the last few decades. Although the effect of this will not be known for many years, DELL Inspiron 1521 Laptop Keyboard
it potentially could mean disaster for the hundreds of millions of people who rely on the glaciers to feed the rivers of northern India during the dry seasons.[16] Some of the lakes present a danger of aglacial lake outburst flood. The Tsho Rolpa glacier lake in the Rolwaling Valley is rated as the most dangerous in Nepal.[17][18] DELL Alienware M17xR2 Laptop Keyboard
The Himalayan region is dotted with hundreds of lakes. Most lakes are found at altitudes of less than 5,000 m, with the size of the lakes diminishing with altitude. Tilicho lake in Nepal in the Annapurna massif is one of the highest lakes in the world. Pangong Tso, HP 519265-001 Laptop Keyboard
which is spread across the border between India and China, and Yamdrok Tso, located in central Tibet, are amongst the largest with surface areas of 700 km², and 638 km², respectively. Other notable lakes include Gurudogmar lake, in North Sikkim, and Tsongmo lake, near the Indo-China border in Sikkim. COMPAQ Presario C700 Laptop Keyboard
The mountain lakes are known to geographers as tarns if they are caused by glacial activity. Tarns are found mostly in the upper reaches of the Himalaya, above 5,500 metres.[19] Lenovo Thinkpad T420 Laptop Keyboard
The Himalayas have a profound effect on the climate of the Indian subcontinent and the Tibetan plateau. They prevent frigid, dry Arctic winds blowing south into the subcontinent, TOSHIBA Satellite A305 Laptop Keyboard
which keeps South Asia much warmer than correspondingtemperate regions in the other continents. It also forms a barrier for the monsoon winds, keeping them from traveling northwards, and causing heavy rainfall in the Terai region. Compaq Presario CQ57 Series Laptop Keyboard
The Himalayas are also believed to play an important part in the formation of Central Asiandeserts, such as the Taklamakan and Gobi.[20] Lenovo 39T7417 Laptop Keyboard
In Hinduism, the Himalaya have also been personified as the god Himavat, the God of snow, who is mentioned in theMahabharata. He is father of Ganga and Saraswati, who became rivers, and Parvati, who married Shiva.[21] DELL Vostro 3450 Laptop Keyboard
Several places in the Himalaya are of religious significance in Hinduism, Jainism, Sikhism, Buddhism, and Islam. A notable example of a religious site is Paro Taktsang, where Padmasambhava is said to have founded Buddhism inBhutan.[22]
HP Mini 210-1014TU Laptop Keyboard
There were over 6,000 monasteries in Tibet.[23] The Tibetan Muslims had their own mosques in Lhasa and Shigatse.[24] HP Pavilion DV6-1002tx Laptop Keyboard
The Tropic of Cancer, also referred to as the Northern tropic, is the circle of latitude on theEarth that marks the most northerly position at which the Sun may appear directly overhead at itszenith. HP 519265-001 Laptop Keyboard
This event occurs once per year, at the time of the June solstice, when the Northern Hemisphere is tilted toward the Sun to its maximum extent. It currently (Year 2013) lies at 23° 26′ 15.143″ north of the Equator.[1] DELL Precision M4500 Laptop Keyboard
Its Southern Hemisphere counterpart, marking the most southerly position at which the Sun may appear directly overhead, is the Tropic of Capricorn. These tropics are two of the five major degree measures or major circles of latitude that mark maps of the Earth, DELL PK130801B00 Laptop Keyboard
besides the Arctic and Antarctic Circles and the Equator. The positions of these circles of latitude (other than the Equator) are dictated by the tilt of the Earth's axis of rotation relative to the plane of its orbit. HP Pavilion DV6-1030us Laptop Keyboard
The imaginary line is called the Tropic of Cancer because when the Sun reaches the zenith at this latitude, it is entering the tropical sign of Cancer (summer solstice). HP Probook 4520S Laptop Keyboard
When it was named, the Sun was also in the direction of the constellation Cancer (Latin for crab). However, this is no longer true due to the precession of the equinoxes. According toInternational Astronomical Union boundaries, the Sun now is in Taurus at the June solstice. SONY 147977821 Laptop Keyboard
According to sidereal astrology, which divides thezodiac into 12 equal parts, the Sun is in Gemini at that time. However, according to tropical astrology, which divides the ecliptic in twelve 30° sectors, SONY 147963021 Laptop Keyboard
starting with the vernal equinox, the Sun is always entering Cancer at this time, as the Earth's axial tilt is most inclined towards the Sun. The word "tropic" itself comes from the Greek tropos, meaning turn, referring to the fact that the sun appears to "turn back" at the solstices. SONY VAIO VGN-CS16M/P laptop keyboard
The Tropic of Cancer currently (Epoch 2012) lies 23° 26′ 16″ [2] north of the Equator. Its position is not fixed, but varies in a complicated manner over time. It is presently drifting south at the rate of almost half a second (0.47″) of latitude per year (it was at exactly 23° 27' in year 1917).[3] See circles of latitude for further information. IBM Thinkpad R40 laptop keyboard
North of Tropic of Cancer are the subtropics and the North Temperate Zone. The equivalent line of latitude south of the Equator is called the Tropic of Capricorn, and the region between the two, centered on the Equator, is the tropics. HP Pavilion DV7-3186cl laptop keyboard
Starting at the Prime Meridian and heading eastwards, the Tropic of Cancer passes through:
Excluding cooler highland regions in China, the climate at the Tropic of Cancer is generally hot and dry except for easterly coastal areas whereorographic rainfall can be very heavy, in some places reaching 4 metres (160 in). SONY VAIO VGN-N320E/W laptop keyboard
Most regions on the Tropic of Cancer experience two distinct season: an extremely hot summer with temperatures often reaching 45 °C (113 °F) and a warm winter with maxima around 22 °C (72 °F). Lenovo ThinkPad Edge E520 laptop keyboard
Most land on or near the Tropic of Cancer is part of the Sahara Desert, whilst to the east the climate is torrid monsoonal with a short wet season from June to September and very little rainfall for the rest of the year. HP Pavilion dv6-2170eo laptop keyboard
The highest mountain on or adjacent to the Tropic of Cancer is Yushan in Taiwan; though it had glaciers descending as low as 2,800 metres (9,190 ft) during the Last Glacial Maximum TOSHIBA Satellite L655-S5153 laptop keyboard
, none survive and at present no glaciers exist within 470 kilometres (290 mi) of the tropic of Cancer; the nearest currently surviving are the Minyong and Baishui in the Himalayas to the north and on Iztaccíhuatl to the south. HP Pavilion DV7-3067cl laptop keyboard
The Southern Hemisphere is part of a rotating astronomical body that lies south of the equator. The word hemisphere(from the Greek word σφαιρα (sphere) +ημι (half)) literally means 'half ball' or "half sphere". It is also that half of the celestial sphere south of the celestial equator. HP Pavilion DV7-3180us laptop keyboard
On Earth the Southern Hemisphere contains all or parts of four continents (Antarctica, Australia, about 9/10 of South America and the southern third of Africa), four oceans (Indian, South Atlantic, Southern, and South Pacific) and most of Oceania. SONY VAIO VGN-FW11S laptop keyboard
Several islands off the Asian continental mainland are also in the Southern Hemisphere. Due to the tilt of Earth's rotation relative to the Sun and the ecliptic plane, HP Pavilion DV6-1122us laptop keyboard
summer is from December to March and winter is from June to September. September 22 or 23 is the vernal equinox and March 20 or 21 is the autumnal equinox. HP Pavilion dv6-2170ee laptop keyboard
In the Southern Hemisphere the sun passes from east to west through the north, although north of the Tropic of Capricorn the mean sun can be directly overhead or due south at midday. SONY VAIO VGN-FS315M laptop keyboard
The Sun rotating through the north causes an apparent right-left trajectory through the sky unlike the left-right motion of the Sun when seen from the Northern Hemisphere as it passes through the southern sky. DELL PK130801B00 laptop keyboard
Sun-cast shadows turn anticlockwise throughout the day and sundials have the hours increasing in the anticlockwise direction. During solar eclipses viewed from a point to the south of the Tropic of Capricorn the Moon moves from left to right on the disc of the Sun (see, for example, TOSHIBA Satellite L655-S5163 laptop keyboard
photos with timings of the Solar eclipse of November 13, 2012), while viewed from a point to the north of the Tropic of Cancer (i.e., in the Northern Hemisphere) the Moon moves from right to left during a solar eclipses. HP Pavilion dv5t-1200se CTO laptop keyboard
Cyclones and tropical storms spin clockwise in the Southern Hemisphere (as opposed to anticlockwise in the Northern Hemisphere) due to the Coriolis effect. COMPAQ Presario C700 Laptop Keyboard
The southern temperate zone, a subsection of the Southern Hemisphere, is nearly all oceanic. This zone includes all of Uruguay, Lesotho, Swaziland, and New Zealand; most of Chile, Argentina, South Africa, andAustralia; and parts of Paraguay, Brazil, Namibia, Botswana, Mozambique, and Madagascar. HP G72-b60US Laptop Keyboard
The South Pole is oriented towards the galactic centre and this, combined with clearer skies, makes for excellent viewing of the night sky from the Southern Hemisphere with brighter and more numerous stars. DELL INSPIRON 1464 Laptop Keyboard
Forests in the Southern Hemisphere have special features which set them aside from the Northern Hemisphere. Both Chile and New Zealand share, for example, unique beech species or Nothofagus. DELL XPS 15 L502X Laptop Keyboard
The eucalyptus is native to Australia but has now gone on to be planted in Southern Africa and Latin America for pulp production and, increasingly, biofuel uses.
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. DELL Vostro 1015 Laptop Keyboard
It may be a change in average weather conditions, or in the distribution of weather around the average conditions (i.e., more or fewer extreme weather events). Climate change is caused by factors that include oceanic processes (such as oceanic circulation), biotic processes, HP 643263-001 Laptop Keyboard
variations insolar radiation received by Earth, plate tectonics and volcanic eruptions, and human-induced alterations of the natural world; these human-induced effects are currently causing global warming, and "climate change" is often used to describe human-specific impacts. SAMSUNG N140 Laptop Keyboard
Scientists actively work to understand past and future climate by using observations and theoretical models. A climate record -- extending deep into the Earth's past -- has been assembled, and continues to be built up, TOSHIBA Mini NB 505-SP0160 Laptop Keyboard
based on geological evidence from borehole temperature profiles, cores removed from deep accumulations of ice, floral andfaunal records, glacial and periglacial processes, stable-isotope and other analyses of sediment layers, and records of past sea levels. IBM 42T4026 laptop keyboard
More recent data are provided by the instrumental record. General circulation models, based on physics, are often used in theoretical approaches to match past climate data, make future projections, Lenovo 3000 G530 4151 laptop keyboard
and link causes and effects in climate change.
The most general definition of climate change is a change in the statistical properties of the climate system when considered over long periods of time, regardless of cause.[1] Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, do not represent climate change. Packard Bell Easynote TM98 laptop keyboard
The term sometimes is used to refer specifically to climate change caused by human activity, as opposed to changes in climate that may have resulted as part of Earth's natural processes.[2] SONY VAIO VGN-N21E/W laptop keyboard
In this sense, especially in the context of environmental policy, the term climate change has become synonymous withanthropogenic global warming. Within scientific journals, HP Pavilion DV7T-4100 laptop keyboard
global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels will affect.[3] SONY VAIO VGN-FS215E laptop keyboard
On the broadest scale, the rate at which energy is received from the sun and the rate at which it is lost to space determine the equilibrium temperature and climate of Earth. This energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions. SONY Vaio PCG-K23 laptop keyboard
Factors that can shape climate are called climate forcings or "forcing mechanisms".[4] These include processes such as variations in solar radiation, variations in the Earth's orbit, mountain-building and continental drift and changes in greenhouse gas concentrations. DELL NSK-DB301 laptop keyboard
There are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the climate system, such as the oceans and ice caps, respond slowly in reaction to climate forcings, while others respond more quickly. TOSHIBA P205-S7469 laptop keyboard
Forcing mechanisms can be either "internal" or "external". Internal forcing mechanisms are natural processes within the climate system itself (e.g., thethermohaline circulation). External forcing mechanisms can be either natural (e.g., changes in solar output) or anthropogenic (e.g., increased emissions of greenhouse gases).
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a sudden cooling due to airbornevolcanic ash reflecting sunlight), slow (e.g. thermal expansion of warming ocean water), or a combination (e.g., sudden loss of albedo in the arctic ocean as sea ice melts, SONY VAIO VGN-NW110D laptop keyboard
followed by more gradual thermal expansion of the water). Therefore, the climate system can respond abruptly, but the full response to forcing mechanisms might not be fully developed for centuri SONY VAIO VGN-N250E/B laptop keyboard
Natural changes in the components of Earth's climate system and their interactions are the cause of internal climate variability, TOSHIBA 9J.N9282.W01 laptop keyboard
or "internal forcings." Scientists generally define the five components of earth's climate system to include atmosphere, hydrosphere, cryosphere, lithosphere (restricted to the surface soils, rocks, and sediments), and biosphere.[5] SONY KFRMBA151B laptop keyboard
The ocean is a fundamental part of the climate system, some changes in it occurring at longer timescales than in theatmosphere, massing hundreds of times more and having very high thermal inertia (such as the ocean depths still lagging today in temperature adjustment from the Little Ice Age).[clarification needed][6] TOSHIBA Satellite l25-s1196 laptop keyboard
Short-term fluctuations (years to a few decades) such as the El Niño-Southern Oscillation, the Pacific decadal oscillation, the North Atlantic oscillation, and the Arctic oscillation, HP Pavilion DV6-1205ee laptop keyboard
represent climate variability rather than climate change. On longer time scales, alterations to ocean processes such as thermohaline circulation play a key role in redistributing heat by carrying out a very slow and extremely deep movement of water and the long-term redistribution of heat in the world's oceans. SAMSUNG Q320 laptop keyboard
Life affects climate through its role in the carbon and water cycles and such mechanisms as albedo, evapotranspiration,cloud formation, and weathering.[7][8][9] Examples of how life may have affected past climate include: glaciation 2.3 billion years ago triggered by the evolution of oxygenic photosynthesis,[10][11] TOSHIBA Satellite M645-S4070 Laptop Keyboard
glaciation 300 million years ago ushered in by long-term burial of decomposition-resistant detritus of vascular land plants (forming coal),[12][13] HP Probook 4515S Laptop Keyboard
termination of the Paleocene-Eocene Thermal Maximum 55 million years ago by flourishing marine phytoplankton,[14][15]reversal of global warming 49 million years ago by 800,000 years of arctic azolla blooms,[16][17] and global cooling over the past 40 million years driven by the expansion of grass-grazer ecosystems.[18][19] SONY VAIO VGN-AR630E Laptop Keyboard
Slight variations in Earth's orbit lead to changes in the seasonal distribution of sunlight reaching the Earth's surface and how it is distributed across the globe. There is very little change to the area-averaged annually averaged sunshine; but there can be strong changes in the geographical and seasonal distribution. SONY VAIO PCG-FR315M Laptop Keyboard
The three types of orbital variations are variations in Earth's eccentricity, changes in the tilt angle of Earth's axis of rotation, andprecession of Earth's axis. Combined together, DELL Latitude D620 Laptop Keyboard
these produce Milankovitch cycles which have a large impact on climate and are notable for their correlation to glacial and interglacial periods,[20] their correlation with the advance and retreat of the Sahara,[20] and for their appearance in the stratigraphic record.[21] DELL Latitude D620 Laptop Keyboard
The IPCC notes that Milankovitch cycles drove the ice age cycles, CO2 followed temperature change "with a lag of some hundreds of years," and that as a feedback amplified temperature change.[22] SAMSUNG N150 Laptop Keyboard
The depths of the ocean have a lag time in changing temperature (thermal inertia on such scale). Upon seawater temperature change, the solubility of CO2 in the oceans changed, as well as other factors impacting air-sea CO2 exchange.[23] HP Pavilion G6-1B59WM Laptop Keyboard
Solar output
The Sun is the predominant source for energy input to the Earth. Both long- and short-term variations in solar intensity are known to affect global climate.
Three to four billion years ago the sun emitted only 70% as much power as it does today. HP G62-367DX Laptop Keyboard
If the atmospheric composition had been the same as today, liquid water should not have existed on Earth. However, there is evidence for the presence of water on the early Earth, in the Hadean[24][25] DELL V119525BS1 Laptop Keyboard
and Archean[26][24] eons, leading to what is known as the faint young Sun paradox.[27] Hypothesized solutions to this paradox include a vastly different atmosphere, SONY Vaio PCG-K33 Laptop Keyboard
with much higher concentrations of greenhouse gases than currently exist.[28] Over the following approximately 4 billion years, the energy output of the sun increased and atmospheric composition changed. SONY VAIO VGN-N325QE/W Laptop Keyboard
The Great Oxygenation Event – oxygenation of the atmosphere around 2.4 billion years ago – was the most notable alteration. TOSHIBA Satellite A205-S4618 Laptop Keyboard
Over the next five billion years the sun's ultimate death as it becomes a red giant and then a white dwarf will have large effects on climate, with the red giant phase possibly ending any life on Earth that survives until that time. HP G61-424CA laptop keyboard
Solar output also varies on shorter time scales, including the 11-year solar cycle[29] and longer-term modulations.[30]Solar intensity variations are considered to have been influential in triggering the Little Ice Age,[31] Packard Bell Easynote TM81 laptop keyboard
and some of the warming observed from 1900 to 1950. The cyclical nature of the sun's energy output is not yet fully understood; it differs from the very slow change that is happening within the sun as it ages and evolves. HP G61-424CA laptop keyboard
Research indicates that solar variability has had effects including the Maunder minimum from 1645 to 1715 A.D., part of the Little Ice Age from 1550 to 1850 A.D. Compaq Presario CQ56-102SE laptop keyboard
that was marked by relative cooling and greater glacier extent than the centuries before and afterward.[32][33] HP G42-265LA laptop keyboard
Some studies point toward solar radiation increases from cyclical sunspot activity affecting global warming, and climate may be influenced by the sum of all effects (solar variation, anthropogenic radiative forcings, etc.).[34][35] TOSHIBA Satellite A305-S6841 laptop keyboard
Interestingly, a 2010 study[36] suggests, “that the effects of solar variability on temperature throughout the atmosphere may be contrary to current expectations.”
In an Aug 2011 Press Release,[37] HP Mini 210-1081NR laptop keyboard
CERN announced the publication in the Nature journal the initial results from itsCLOUD experiment. The results indicate that ionisation from cosmic rays significantly enhances aerosol formation in the presence of sulphuric acid and water, HP G42-265LA laptop keyboard
but in the lower atmosphere where ammonia is also required, this is insufficient to account for aerosol formation and additional trace vapours must be involved. The next step is to find more about these trace vapours, including whether they are of natural or human origin. TOSHIBA Satellite A305-S6829 laptop keyboard
Volcanic eruptions release gases and particulates into the atmosphere. Eruptions large enough to affect climate occur on average several times per century, and cause cooling (by partially blocking the transmission of solar radiation to the Earth's surface) for a period of a few years. TOSHIBA PK13AT10600 laptop keyboard
The eruption of Mount Pinatubo in 1991, the second largest terrestrial eruption of the 20th century[40] (after the 1912 eruption of Novarupta[41]) affected the climate substantially. Global temperatures decreased by about 0.5 °C (0.9 °F). SONY VGN-FE21B laptop keyboard
The eruption of Mount Tambora in 1815 caused the Year Without a Summer.[42] Much larger eruptions, known as large igneous provinces, occur only a few times every hundred million years, but may cause global warming and mass extinctions.[43] COMPAQ Presario CQ50-210US laptop keyboard
Volcanoes are also part of the extended carbon cycle. Over very long (geological) time periods, they release carbon dioxide from the Earth's crust and mantle, counteracting the uptake by sedimentary rocks and other geological carbon dioxide sinks. DELL V119525BS1 laptop keyboard
The US Geological Survey estimates are that volcanic emissions are at a much lower level than the effects of current human activities, which generate 100–300 times the amount of carbon dioxide emitted by volcanoes.[44] TOSHIBA Satellite C650-182 Laptop Keyboard
A review of published studies indicates that annual volcanic emissions of carbon dioxide, including amounts released from mid-ocean ridges, volcanic arcs, and hot spot volcanoes, are only the equivalent of 3 to 5 days of human caused output. ASUS F3M Laptop Keyboard
The annual amount put out by human activities may be greater than the amount released bysupererruptions, the most recent of which was the Toba eruption in Indonesia 74,000 years ago.[45] Lenovo 63Y0047 Laptop Keyboard
Although volcanoes are technically part of the lithosphere, which itself is part of the climate system, the IPCC explicitly defines volcanism as an external forcing agent.[46]
Plate tectonics HP Pavilion dv6-3107ax Laptop Keyboard
Over the course of millions of years, the motion of tectonic plates reconfigures global land and ocean areas and generates topography. This can affect both global and local patterns of climate and atmosphere-ocean circulation.[47] SONY VAIO VGN-C2S Series Laptop Keyboard
The position of the continents determines the geometry of the oceans and therefore influences patterns of ocean circulation. The locations of the seas are important in controlling the transfer of heat and moisture across the globe, and therefore, in determining global climate. HP 488590-001 Laptop Keyboard
A recent example of tectonic control on ocean circulation is the formation of the Isthmus of Panama about 5 million years ago, which shut off direct mixing between the Atlantic andPacific Oceans. TOSHIBA P000482730 Laptop Keyboard
This strongly affected the ocean dynamics of what is now the Gulf Stream and may have led to Northern Hemisphere ice cover.[48][49] During the Carboniferous period, about 300 to 360 million years ago, plate tectonics may have triggered large-scale storage of carbon and increasedglaciation.[50] SONY 147977821 Laptop Keyboard
Geologic evidence points to a "megamonsoonal" circulation pattern during the time of the supercontinent Pangaea, and climate modeling suggests that the existence of the supercontinent was conducive to the establishment of monsoons.[51] TOSHIBA Tecra M9-S5514 Laptop Keyboard
The size of continents is also important. Because of the stabilizing effect of the oceans on temperature, yearly temperature variations are generally lower in coastal areas than they are inland. A larger supercontinent will therefore have more area in which climate is strongly seasonal than will several smaller continents or islands. GATEWAY NV-54 Laptop Keyboard
Of most concern in these anthropogenic factors is the increase in CO2 levels due to emissions from fossil fuel combustion, followed by aerosols(particulate matter in the atmosphere) and the CO2 released by cement manufacture. FUJITSU Lifebook P1510 Laptop Keyboard
Other factors, including land use, ozone depletion, animal agriculture[54] and deforestation, are also of concern in the roles they play – both sEvidence for climatic change is taken from a variety of sources that can be used to reconstruct past climates. FUJITSU Lifebook P1610 Laptop Keyboard
Reasonably complete global records of surface temperature are available beginning from the mid-late 19th century. DELL Precision M4500 Laptop Keyboard
For earlier periods, most of the evidence is indirect—climatic changes are inferred from changes in proxies, indicators that reflect climate, such as vegetation, ice cores,[55]dendrochronology, sea level change, and glacial geology.
Temperature measurements and proxies HP Pavilion DV7t-3100 laptop keyboard
The instrumental temperature record from surface stations was supplemented by radiosonde balloons, extensive atmospheric monitoring by the mid-20th century, and, from the 1970s on, HP Pavilion dv6-2150es laptop keyboard
withglobal satellite data as well. The 18O/16O ratio in calcite and ice core samples used to deduce ocean temperature in the distant past is an example of a temperature proxy method, as are other climate metrics noted in subsequent categories. HP Pavilion dv6-3107ax laptop keyboard
Historical and archaeological evidence
Main article: Historical impacts of climate change
Climate change in the recent past may be detected by corresponding changes in settlement and agricultural patterns.[56] SONY VAIO VGN-FS415E laptop keyboard
Archaeological evidence, oral history and historical documents can offer insights into past changes in the climate. Climate change effects have been linked to the collapse of various civilizations.[56] HP Pavilion DV7-3165dx laptop keyboard
eparately and in conjunction with other factors – in affecting climate, microclimate, and measures of climate variables.
Glaciers are considered among the most sensitive indicators of climate change.[57] Their size is determined by a mass balance between snow input and melt output. SONY VAIO VGN-NW25GF laptop keyboard
As temperatures warm, glaciers retreat unless snow precipitation increases to make up for the additional melt; the converse is also true.
Glaciers grow and shrink due both to natural variability and external forcings. Compaq Presario CQ71-317EA laptop keyboard
Variability in temperature, precipitation, and englacial and subglacial hydrology can strongly determine the evolution of a glacier in a particular season. Therefore, FUJITSU Lifebook P1610 laptop keyboard
one must average over a decadal or longer time-scale and/or over a many individual glaciers to smooth out the local short-term variability and obtain a glacier history that is related to climate. HP Pavilion dv6-2129ev laptop keyboard
A world glacier inventory has been compiled since the 1970s, initially based mainly on aerial photographs and maps but now relying more on satellites. This compilation tracks more than 100,000 Packard Bell NEW90 laptop keyboard
glaciers covering a total area of approximately 240,000 km2, and preliminary estimates indicate that the remaining ice cover is around 445,000 km2. The World Glacier Monitoring Service collects data annually on glacier retreat and glacier mass balance From this data, SONY VAIO VGN-FS640/W laptop keyboard
glaciers worldwide have been found to be shrinking significantly, with strong glacier retreats in the 1940s, stable or growing conditions during the 1920s and 1970s, and again retreating from the mid-1980s to present.[58] HP 405963-001 laptop keyboard
The most significant climate processes since the middle to late Pliocene (approximately 3 million years ago) are the glacial and interglacial cycles. The present interglacial period (the Holocene) has lasted about 11,700 years.[59] HP Pavilion G6-1223TX Laptop Keyboard
Shaped by orbital variations, responses such as the rise and fall ofcontinental ice sheets and significant sea-level changes helped create the climate. Other changes, including Heinrich events, Dansgaard–Oeschger eventsand the Younger Dryas, HP G42-364LA Laptop Keyboard
however, illustrate how glacial variations may also influence climate without the orbital forcing. SONY VAIO VGN-FS315M Laptop Keyboard
Glaciers leave behind moraines that contain a wealth of material—including organic matter, quartz, and potassium that may be dated—recording the periods in which a glacier advanced and retreated. DELL Vostro PP37L Laptop Keyboard
Similarly, by tephrochronological techniques, the lack of glacier cover can be identified by the presence of soil or volcanic tephra horizons whose date of deposit may also be ascertained. SONY VAIO VGN-C2S Series Laptop Keyboard
The decline in Arctic sea ice, both in extent and thickness, over the last several decades is further evidence for rapid climate change.[60] Sea ice is frozen seawater that floats on the ocean surface. It covers millions of square miles in the polar regions, HP pavilion DV7-1000 Laptop Keyboard
varying with the seasons. In the Arctic, some sea ice remains year after year, whereas almost all Southern Ocean or Antarctic sea ice melts away and reforms annually. Satellite observations show that Arctic sea ice is now HP G42-364LA Laptop Keyboard
A change in the type, distribution and coverage of vegetation may occur given a change in the climate. Some changes in climate may result in increased precipitation and warmth, TOSHIBA 9J.N7482.901 Laptop Keyboard
resulting in improved plant growth and the subsequent sequestration of airborne CO2. A gradual increase in warmth in a region will lead to earlier flowering and fruiting times, driving a change in the timing of life cycles of dependent organisms. Conversely, TOSHIBA Satellite U305-S2804 Laptop Keyboard
cold will cause plant bio-cycles to lag.[62] Larger, faster or more radical changes, however, may result in vegetation stress, rapid plant loss and desertification in certain circumstances.[63][64] HP 597635-001 Laptop Keyboard
An example of this occurred during the Carboniferous Rainforest Collapse (CRC), an extinction event 300 million years ago. At this time vast rainforests covered the equatorial region of Europe and America. Compaq Presario CQ57 Series Laptop Keyboard
Climate change devastated these tropical rainforests, abruptly fragmenting the habitat into isolated 'islands' and causing the extinction of many plant and animal species.[63] DELL Vostro 1014 Laptop Keyboard
Satellite data available in recent decades indicates that global terrestrial net primary production increased by 6% from 1982 to 1999, with the largest portion of that increase in tropical ecosystems, then decreased by 1% from 2000 to 2009.[65][66]
Pollen analysisLenovo 3000 N200 Laptop Keyboard
Palynology is the study of contemporary and fossil palynomorphs, including pollen. Palynology is used to infer the geographical distribution of plant species, which vary under different climate conditions. HP Pavilion zv6223ea Laptop Keyboard
Different groups of plants have pollen with distinctive shapes and surface textures, and since the outer surface of pollen is composed of a very resilient material, they resist decay. Changes in the type of pollen found in different layers of sediment in lakes, bogs, or river deltas indicate changes in plant communities. These changes are often a sign of a changing climate. Lenovo Thinkpad T520 Laptop Keyboard
As an example, palynological studies have been used to track changing vegetation patterns throughout the Quaternary glaciations[69] and especially since the last glacial maximum.[70] ACER Aspire 4736Z laptop keyboard
Past precipitation can be estimated in the modern era with the global network of precipitation gauges. Surface coverage over oceans and remote areas is relatively sparse, but, reducing reliance on interpolation, satellite data has been available since the 1970s.[72] TOSHIBA Satellite L755-S5216 laptop keyboard
Quantification of climatological variation of precipitation in prior centuries and epochs is less complete but approximated using proxies such as marine sediments, ice cores, cave stalagmites, and tree rings.[73] HP Pavilion DV6z artist edition 2 laptop keyboard
Climatological temperatures substantially affect precipitation. For instance, during the Last Glacial Maximum of 18,000 years ago, thermal-driven evaporation from the oceans onto continental landmasses was low, HP Pavilion dv6-3142se laptop keyboard
causing large areas of extreme desert, including polar deserts (cold but with low rates of precipitation).[71] In contrast, the world's climate was wetter than today near the start of the warm Atlantic Period of 8000 years ago.[71] TOSHIBA Satellite P300-ST3712 laptop keyboard
Estimated global land precipitation increased by approximately 2% over the course of the 20th century, though the calculated trend varies if different time endpoints are chosen, HP G42-265LA laptop keyboard
complicated by ENSO and other oscillations, including greater global land precipitation in the 1950s and 1970s than the later 1980s and 1990s despite the positive trend over the century overall.[72][74][75] Similar slight overall increase in global river runoff and in average soil moisture has been perceived.[74] SONY VAIO VGN-FS620 laptop keyboard
Dendroclimatology
Dendroclimatology is the analysis of tree ring growth patterns to determine past climate variations.[76] Wide and thick rings indicate a fertile, well-watered growing period, whilst thin, narrow rings indicate a time of lower rainfall and less-than-ideal growing conditions. HP Pavilion dv3-2155mx laptop keyboard
Ice cores
Analysis of ice in a core drilled from an ice sheet such as the Antarctic ice sheet, can be used to show a link between temperature and global sea level variations. The air trapped in bubbles in the ice can also reveal the CO2 variations of the atmosphere from the distant past, TOSHIBA PK130BH2A00 laptop keyboard
well before modern environmental influences. The study of these ice cores has been a significant indicator of the changes in CO2 over many millennia, and continues to provide valuable information about the differences between ancient and modern atmospheric conditions. SONY VAIO VGN-CR123E laptop keyboard
Animals
Remains of beetles are common in freshwater and land sediments. Different species of beetles tend to be found under different climatic conditions. Given the extensive lineage of beetles whose genetic makeup has not altered significantly over the millennia, Lenovo ThinkPad T510-4339 laptop keyboard
knowledge of the present climatic range of the different species, and the age of the sediments in which remains are found, past climatic conditions may be inferred.[77] HP Pavilion dv6-2130ca laptop keyboard
Similarly, the historical abundance of various fish species has been found to have a substantial relationship with observed climatic conditions.[78]Changes in the primary productivity of autotrophs in the oceans can affect marine food webs.[79] Packard Bell Easynote TK85 laptop keyboard
Sea level change
Main articles: Sea level and Current sea level rise
Global sea level change for much of the last century has generally been estimated using tide gauge measurements collated over long periods of time to give a long-term average. DELL Inspiron 1750 Laptop Keyboard
More recently, altimeter measurements — in combination with accurately determined satellite orbits — have provided an improved measurement of global sea level change.[80] HP Pavilion DV6z artist edition 2 Laptop Keyboard
To measure sea levels prior to instrumental measurements, scientists have dated coral reefs that grow near the surface of the ocean, coastal sediments, marine terraces, ooids in limestones, DELL Vostro 3550 Laptop Keyboard
and nearshore archaeological remains. The predominant dating methods used are uranium series and radiocarbon, with cosmogenic radionuclides being sometimes used to date terraces that have experienced relative sea level fall. HP Pavilion dv6-2125ef laptop keyboard
In the early Pliocene, global temperatures were 1–2˚C warmer than the present temperature, yet sea level was 15–25 meters higher than today.[81] HP Pavilion dv6-2110ev laptop keyboard
Rhododendron is the national flower of himalayan republic of Nepal. Rhododendron is a genus characterized by shrubs and small to (rarely) large trees, the smallest species growing to 10–100 cm (3.9–39 in) tall, and the largest, R. protistum var. giganteum, reported to 30 m (98 ft) tall.[4][5] SONY VAIO VGN-N31Z/W laptop keyboard
The leaves are spirally arranged; leaf size can range from 1–2 cm (0.39–0.79 in) to over 50 cm (20 in), exceptionally 100 cm (39 in) in R. sinogrande. They may be either evergreen or deciduous. ACER TravelMate 6252 laptop keyboard
In some species, the undersides of the leaves are covered with scales (lepidote) or hairs (indumentum). Some of the best known species are noted for their many clusters of large flowers. SONY VGN-FE11M laptop keyboard
There are alpine species with small flowers and small leaves, and tropical species such as section Vireya that often grow as epiphytes. Species in this genus may be part of the heath complex in oak-heath forests in eastern North America.[6][7] TOSHIBA Satellite L750-ST4NX1 laptop keyboard
Both species and hybrid rhododendrons (including azaleas) are used extensively as ornamental plants in landscaping in many parts of the world, and many species and cultivars are grown commercially for the nursery trade. Rhododendrons are often valued in landscaping for their structure, size, ASUS X53S laptop keyboard
flowers, and the fact that many of them are evergreen.[12]Azaleas are frequently used around foundations and occasionally as hedges, and many larger-leafed rhododendrons lend themselves well to more informal plantings and woodland gardens, Acer eMachines E640 laptop keyboard
or as specimen plants. In some areas, larger rhododendrons can be pruned to encourage more tree-like form, with some species such as R. arboreum and R. falconerieventually growing to 10–15 m or more tall.[12] TOSHIBA Satellite L655-S5107 laptop keyboard
Like other ericaceous plants, most rhododendrons prefer acid soils with a pH of roughly 4.5-5.5; some tropical Vireyas and a few other rhododendron species grow as epiphytes and require a planting mix similar to orchids. Rhododendrons have fibrous roots and prefer well-drained soils high in organic material. HP Pavilion DV6z artist edition 2 laptop keyboard
In areas with poorly drained or alkaline soils, rhododendrons are often grown in raised beds using media such as composted pine bark.[24] Mulching and careful watering are important, especially before the plant is established. SONY VAIO VGN-N250E/B laptop keyboard
A new calcium-tolerant stock of rhododendrons (patented as 'Inkarho') has been exhibited at the RHS Chelsea Flower Showin London (2011). SONY Vaio PCG-K315S laptop keyboard
Individual hybrids of rhododendrons have been grafted on to a rootstock on a single rhododendron plant that was found growing in a chalk quarry. The rootstock is able to grow in calcium-rich soil up to a pH of 7.5.[25][26] HP Pavilion DV7-3067nr laptop keyboard
Some species of rhododendron are poisonous to grazing animals because of a toxin called grayanotoxin in their pollen and nectar. People have been known to become ill from eating honey made by bees feeding on rhododendron and azalea flowers. HP G42-380LA Laptop Keyboard
Xenophon described the odd behavior of Greek soldiers after having consumed honey in a village surrounded by Rhododendron ponticum during the march of the Ten Thousand in 401 BC. GATEWAY NV-53 Laptop Keyboard
Pompey's soldiers reportedly suffered lethal casualties following the consumption of honey made from Rhododendron deliberately left behind by Pontic forces in 67 BC during the Third Mithridatic War. HP 646568-001 Laptop Keyboard
Later, it was recognized that honey resulting from these plants has a slightly hallucinogenic and laxative effect.[27] The suspect rhododendrons are Rhododendron ponticum and Rhododendron luteum (formerly Azalea pontica), ACER Aspire One D150-1920 Laptop Keyboard
both found in northern Asia Minor. Eleven similar cases have been documented in Istanbul, Turkey during the 1980s.[28] Rhododendron is extremely toxic to horses, with some animals dying within a few hours of ingesting the plant, although most horses tend to avoid it if they have access to good forage. HP AEUT5U00010 Laptop Keyboard
The effects of R. ponticum was mentioned in the 2009 filmSherlock Holmes as a proposed way to arrange a fake execution.[29] It was also mentioned in the third episode of Season 2 of BBC's Sherlock (TV series), and has been speculated to have been a part of Sherlock's fake death scheme. ACER Aspire One D150-1920 Laptop Keyboard
Rhododendrons are grown commercially in many areas for sale, and are occasionally collected in the wild, a practice now rare in most areas. Larger commercial growers often ship long distances; in the United States, HP AEUT5U00010 Laptop Keyboard
most of them are located on the west coast (Oregon, Washington state and California). Large-scale commercial growing often selects for different characteristics that hobbyist growers might want, APPLE A1278 Laptop Keyboard
such as resistance to root rot when overwatered, ability to be forced into budding early, ease of rooting or other propagation, and saleability.[13] ACER 9J.N0F82.A1D Laptop Keyboard
In the Indian state of Himachal Pradesh, rhododendron flowers have been used for some time to make popular fruit and flower wines. The industry is promoted by the state government with tax benefits, looking to promote this industry as a full-fledged subclass of its economy.[14] HP G72-b66US Laptop Keyboard
Rhododendron arboreum (lali guransh) is the national flower of Nepal. R. ponticum is the state flower of Indian-administered Kashmir and Pakistan-controlled Kashmir. Rhododendron niveum is the state tree of Sikkim in India. ACER 9J.N0F82.A1D Laptop Keyboard
Rhododendron is also the state tree of the state of Uttarakhand, India. Themountain laurel (Kalmia latifolia) is the state flower of the state of Pennsylvania, in the United States. HP G72-b66US Laptop Keyboard
Rhododendron maximum, the most widespread rhododendron of the Appalachian Mountains, is the state flower of West Virginia, and is in the Flag of West Virginia. Rhododendron macrophyllum, a widespread rhododendron of the Pacific Northwest, is the state flower of Washington. HP Mini 110-3180sv Laptop Keyboard
The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters. Lenovo 3000 N200 Laptop Keyboard
It was formed by the fusion of Indian and Australian plates 43 million years ago.[1] Recent studies, and seismic events such as the 2012 Indian Ocean earthquake, DELL Vostro 3450 Laptop Keyboard
suggest that the Indo-Australian Plate may be in the process of breaking up into two separate plates due primarily to stresses induced by the collision of the Indo-Australian Plate with Eurasia along the Himalayas.[2] HP G72-b60SF laptop keyboard
The eastern part (Australia) is moving northward at the rate of 5.6 cm per year while the western part (India) is moving only at the rate of 3.7 cm per year due to impediment by Himalayas. HP Mini 110-3180sv laptop keyboard
This differential movement is resulting in the compression of the plate near its center at Sumatra and a potential division into Indian and Australian Plates.[3][4][5] The two protoplates or subplates are generally referred to as the Indian Plate and the Australian Plate. LENOVO IdeaPad S10 20015 laptop keyboard
A third Capricorn Plate may also be separating off of the west side of the Indian subplate.[6]
The Indian subcontinent, Meganesia (Australia, New Guinea, and Tasmania), New Zealand, HP Mini 110-3180sv laptop keyboard
and New Caledonia are all fragments of the ancient supercontinent of Gondwana. Seafloor spreading separated these land masses from one another, but as the spreading centers became inactive the land masses fused into a single plate. Lenovo ThinkPad Edge E125 laptop keyboard
Recent GPS measurement in Australia confirms the plate’s velocity of 67 mm/yr at 35 degrees east of north . Note also the same directions and velocities for points at Auckland, Christmas Island and southern India. HP Pavilion dv6-3230us laptop keyboard
A slight difference in local direction at Auckland is presumed due to a slight buckling of the plate there, where it is being compressed by the Pacific Plate. DELL Inspiron 6400 Laptop Keyboard
The northeasterly side is a complex but generally convergent boundary with the Pacific Plate. The Pacific Plate is subducting under the Australian Plate, ACER K052030A1 laptop keyboard
which forms the Tonga and Kermadec Trenches, and the parallel Tonga and Kermadec island arcs. It has also uplifted the eastern parts of New Zealand'sNorth Island.
The continent of Zealandia, TOSHIBA NSK-TAJ01 Laptop Keyboard
which separated from Australia 85 million years ago and stretches from New Caledonia in the north to New Zealand’s subantarctic islands in the south, is now being torn apart along the transform boundary marked by the Alpine Fault. ACER Aspire 7741G Laptop Keyboard
South of New Zealand the boundary becomes a transitional transform-convergent boundary, the Macquarie Fault Zone, where the Australian Plate is beginning to subduct under the Pacific Plate along the Puysegur Trench. Extending southwest of this trench is the Macquarie Ridge. ACER Aspire 7741G Laptop Keyboard
The southerly side is a divergent boundary with the Antarctic Plate called the Southeast Indian Ridge (SEIR). The westerly side is a transform boundary with the Arabian Plate called the Owen Fracture Zone, and a divergent boundary with the African Plate called the Central Indian Ridge (CIR). SONY KFRMBA152B Laptop Keyboard
The northerly side of the Indo-Australian Plate is a convergent boundary with the Eurasian Plate forming the Himalaya and Hindu Kush mountains. HP Pavilion dv6-3001so Laptop Keyboard
The northwest side of the Indo-Australian plate forms a subducting boundary with the Eurasian plate on the borders of the Indian Ocean from Bangladesh, toMyanmar to the south-west of Indonesian islands of Sumatra and Java. HP HDX18-1100 CTO Laptop Keyboard
The subducting boundary through Indonesia is not parallel to the biogeographical Wallace line that separates the indigenous fauna of Asia from that ofAustralasia. The Eastern islands of Indonesia lie mainly on the Eurasian Plate, but have Australasian-related fauna and flora. Southeasterly lies theSunda Shelf. TOSHIBA Satellite C655-S9521D Laptop Keyboard
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which forms thecontinents and the areas of shallow seabed close to their shores, known as continental shelves. HP Pavilion dv6-2160ep laptop keyboard
This layer is sometimes called sial because there is more felsic, or granitic, bulk composition, which lies in contrast to the oceanic crust, called sima because of the mafic or basaltic rock. (Based on the change in velocity of seismic waves, Packard Bell PEW91 laptop keyboard
it is believed that at a certain depth sial becomes close in its physical properties to sima. This line is called the Conrad discontinuity.)
Consisting mostly of granitic rock, continental crust has a density of about 2.7 g/cm3 and is lessdense than the material of the Earth's mantle (density of about 3.3 g/cm3), HP Pavilion dv6-2159tx laptop keyboard
which consists of mafic rock. Continental crust is also less dense than oceanic crust (density of about 2.9 g/cm3), though it is considerably thicker; mostly 25 to 70 km versus the average oceanic thickness of around 7–10 km. DELL 0M711P laptop keyboard
About 40% of the Earth's surface is now overlaid by continental crust.[1] Continental crust makes up about 70% of the volume of Earth's crust.[2] SONY VAIO VGN-CR13/B laptop keyboard
In contrast to the persistence of continental crust, the size, shape, and number of continents are constantly changing through geologic time. Different tracts rift apart, collide and recoalesce as part of a grand supercontinent cycle.[4] There are currently about 7 billion cubic kilometers of continental crust, SONY 148701322 laptop keyboard
but this quantity varies because of the nature of the forces involved. The relative permanence of continental crust contrasts Packard Bell Easynote TK85 laptop keyboard
active margins of the two meet in subduction zones, the oceanic crust is typically subducted back into the mantle. Continental crust is rarely subducted (this may occur where continental crustal blocks collide and overthicken, HP Pavilion dv6-3001so laptop keyboard
causing deep melting under mountain belts such as the Himalayas or the Alps). For this reason the oldest rocks on Earth are within thecratons or cores of the continents, rather than in repeatedly recycled oceanic crust; the oldest intact crustal fragment is the Acasta Gneiss at 4.01 Ga, HP HDX18-1100 CTO laptop keyboard
while the oldest oceanic crust (located on the Pacific Plate offshore of Kamchatka) is no older than Jurassic (~180 Ma). Continental crust and the rock layers that lie on and within it are thus the best archive of Earth history.[1][5] SONY VAIO VGN-N21E/W laptop keyboard
The height of mountain ranges is usually related to the thickness of crust. This results from the isostasy associated with orogeny (mountain formation). The crust is thickened by the compressive forces related to subduction or continental collision. HP Pavilion dv5-1118tx laptop keyboard
The buoyancy of the crust forces it upwards, the forces of the collisional stress balanced by gravity and erosion. This forms a keel or mountain root beneath the mountain range, which is where the thickest crust is found.[6] The thinnest continental crust is found in rift zones, HP AEUT5U00010 laptop keyboard
where the crust is thinned by detachment faulting and eventually severed, replaced by oceanic crust. The edges of continental fragments formed this way (both sides of the Atlantic Ocean, for example) are termed passive margins. HP Mini 110-3504tu laptop keyboard
The high temperatures and pressures at depth, often combined with a long history of complex distortion, cause much of the lower continental crust to be metamorphic - the main exception to this being recent igneous intrusions. SONY VGN-FE21H laptop keyboard
Igneous rock may also be "underplated" to the underside of the crust, i.e. adding to the crust by forming a layer immediately beneath it.
Continental crust is produced and (far less often) destroyed mostly by plate tectonic processes, especially at convergent plate boundaries. TOSHIBA Satellite U305-S2812 Laptop Keyboard
Additionally, continental crustal material is transferred to oceanic crust by sedimentation. New material can be added to the continents by the partial melting of oceanic crust at subduction zones, causing the lighter material to rise as magma, forming volcanoes. GATEWAY M-6319 Laptop Keyboard
Also, material can be accreted horizontally when volcanic island arcs, seamounts or similar structures collide with the side of the continent as a result of plate tectonic movements. HP 634139-001 Laptop Keyboard
Continental crust is also lost through erosion and sediment subduction, tectonic erosion of forearcs, delamination, and deep subduction of continental crust in collision zones.[7] TOSHIBA Satellite L655-S5083 Laptop Keyboard
Many theories of crustal growth are controversial, including rates of crustal growth and recycling, whether the lower crust is recycled differently than the upper crust and over how much of Earth history plate tectonics has operated and so could be the dominant mode of continental crust formation and destruction.[8] ACER Aspire 5742 Laptop Keyboard
It is a matter of debate whether the amount of continental crust has been increasing, decreasing, or remaining constant over geological time. One model indicates that at prior to 3.7 Ga ago continental crust constituted less than 10% of the present amount.[9] HP pavilion DV7-1000 Laptop Keyboard
By 3.0 Ga ago the amount was about 25%, and following a period of rapid crustal evolution it was about 60% of the current amount by 2.6 Ga ago.[10] The growth of continental crust appears to have occurred in spurts of increased activity corresponding to five episodes of increased production through geologic time.[11] TOSHIBA Satellite A300 Laptop Keyboard
The Tibetan Plateau (Tibetan: བོད་ས་མཐོ།, Wylie: bod sa mtho), also known in China as theQinghai-Tibet (Qingzang) Plateau (Chinese: pinyin: Qīngzàng Gāoyuán) orHimalayan Plateau is a vast, elevated plateau in Central Asia[1][2][3][4] or East Asia[5][6][7][8] TOSHIBA Satellite A110 Series Laptop Keyboard
covering most of the Tibet Autonomous Region and Qinghai Province in western China, as well as part of Ladakh in Jammu and Kashmir state of India. It stretches approximately 1,000 kilometres (620 mi) SONY VGN-FE670G Laptop Keyboard
north to south and 2,500 kilometres (1,600 mi) east to west. With an average elevation exceeding 4,500 metres (14,800 ft), the Tibetan Plateau is sometimes called "the Roof of the World" and is the world's highest and largest plateau, HP COMPAQ NX6310 Laptop Keyboard
with an area of 2,500,000 square kilometres (970,000 sq mi) (about four times the size of France).[9] Sometimes termed the "Third Pole", the Tibetan Plateau is the headwaters of thedrainage basins of most of the streams in surrounding regions. DELL INSPIRON 1464 Laptop Keyboard
Its tens of thousands ofglaciers and other geographical and ecological features serve as a "water tower" storing water and maintaining flow. The impact of global warming on the Tibetan Plateau is of intense scientific interest.[10] SONY Vaio PCG-K315S laptop keyboard
The Tibetan Plateau is bounded on the north by a broad escarpment where the altitude drops from around 5,000 metres (16,000 ft) to 1,500 metres (4,900 ft) in less than 150 kilometres (93 mi). Along the escarpment is a range of mountains. TOSHIBA Satellite C655-S5141 laptop keyboard
In the west the Kunlun Mountains separate the plateau from the Tarim Basin. About half way across the Tarim the bounding range becomes the Altyn-Tagh and the Kunluns, by convention, HP Mini 110-3504tu laptop keyboard
continu B e somewhat to the south. In the 'V' formed by this split is the western part of the Qaidamasin. The Altyn-Tagh ends near the Dangjin pass on theDunhuang-Golmud road. Lenovo Thinkpad T520 Laptop Keyboard
To the west are short ranges called the Danghe, Yema, Shule and Tulai Nanshans. The easternmost range is the Qilian Mountains. The line of mountains continues east of the plateau as the Qin Mountains which separate the Ordos Region from Sichuan. SONY VGN-FE11H Laptop Keyboard
North of the mountains runs the Gansu or Hexi Corridor which was the main silk-road route from China proper to the west. COMPAQ Presario C700 Laptop Keyboard
The plateau is a high-altitude arid steppe interspersed with mountain ranges and large brackish lakes. Annual precipitation ranges from 100 to 300 millimetres (3.9 to 12 in) and falls mainly as hailstorms. Lenovo 45N2240 Laptop Keyboard
The southern and eastern edges of the steppe have grasslands which can sustainably support populations of nomadic herdsmen, although frost occurs for six months of the year. SONY VGN-FE550G Laptop Keyboard
Permafrost occurs over extensive parts of the plateau. Proceeding to the north and northwest, the plateau becomes progressively higher, colder and drier, until reaching the remote Changthang region in the northwestern part of the plateau. Lenovo IdeaPad Y710 Laptop Keyboard
Here the average altitude exceeds 5,000 metres (16,000 ft) and winter temperatures can drop to −40 °C (−40 °F). As a result of this extremely inhospitable environment, the Changthang region (together with the adjoining Kekexili region) is the least populous region in Asia, DELL Latitude D830 Laptop Keyboard
and the third least populous area in the world afterAntarctica and northern Greenland.
The Himalayas are among the youngest mountain ranges on the planet and consist mostly of uplifted sedimentary andmetamorphic rock. TOSHIBA Satellite U305-S2812 Laptop Keyboard
According to the modern theory of plate tectonics, their formation is a result of a continental collision or orogeny along the convergent boundary between the Indo-Australian Plate and the Eurasian Plate. They are referred to as fold mountains. GATEWAY M-6319 Laptop Keyboard
The collision began in the Upper Cretaceous period about 70 million years ago, when the north-moving Indo-Australian Plate, moving at about 15 cm per year, collided with the Eurasian Plate. HP 634139-001 Laptop Keyboard
About 50 million years ago, this fast moving Indo-Australian plate had completely closed the Tethys Ocean, the existence of which has been determined by sedimentary rocks settled on the ocean floor, TOSHIBA Satellite L655-S5083 Laptop Keyboard
and the volcanoes that fringed its edges. Since these sediments were light, they crumpled into mountain ranges rather than sinking to the floor. The Indo-Australian plate continues to be driven horizontally below the Tibetan plateau, which forces the plateau to move upwards, the plateau is still rising about 5 mm per year. ACER Aspire 5742 Laptop Keyboard
Monsoons are caused by the larger amplitude of the seasonal cycle of land temperature compared to that of nearby oceans. This differential warming happens because heat in the ocean is mixed vertically through a "mixed layer" that may be fifty meters deep, HP pavilion DV7-1000 Laptop Keyboard
through the action of wind and buoyancy-generated turbulence, whereas the land surface conducts heat slowly, with the seasonal signal penetrating perhaps a meter or so. Additionally, the specific heat capacity of liquid water is significantly higher than that of most materials that make up land. TOSHIBA Satellite A300 Laptop Keyboard
Together, these factors mean that the heat capacity of the layer participating in the seasonal cycle is much larger over the oceans than over land, with the consequence that the air over the land warms faster and reaches a higher temperature than the air over the ocean.[15] IBM ThinkPad T42 laptop keyboard
The hot air over the land tends to rise, creating an area of low pressure. This creates a steady wind blowing toward the land, bringing the moist near-surface air over the oceans with it. Similar rainfall is caused by the moist ocean air being lifted upwards by mountains, surface heating, DELL Inspiron N4050 laptop keyboard
convergence at the surface, divergence aloft, or from storm-produced outflows at the surface. However the lifting occurs, the air cools due expansion in lower pressure, which in turn produces condensation. GATEWAY MT3707 laptop keyboard
In winter, the land cools off quickly, but the ocean keeps the heat longer. The hot air over the ocean rises, creating a low pressure area and a breeze from land to ocean while a large area of drying high pressure is formed over the land, increased by wintertime cooling.[15] HP Pavilion dv6-3050tx laptop keyboard
Monsoons are similar to sea and land breezes, a term usually referring to the localized, diurnal (daily) cycle of circulation near coastlines everywhere, but they are much larger in scale, stronger and seasonal.[16] SONY VGN-FE48E laptop keyboard
The seasonal monsoon wind shift and weather associated with the heating and cooling of the Tibetan plateau is the strongest such monsoon on Earth.
Today, Tibet is an important heating surface of the atmosphere. Lenovo Thinkpad T520 laptop keyboard
However, during the Last Ice Age a c. 2,400,000 square kilometres (930,000 sq mi) ice sheet covered the plateau.[17][18][19] Due to its great extent, this glaciation in the subtropics was an important element of climate forcing. Compaq Presario CQ71-403SA laptop keyboard
With a much lower latitude, the ice in Tibet reflected at least 4 times more radiation energy per unit area into space than ice at higher latitudes. Thus, what at present adds heat to the atmosphere subtracted it instead.[20]
This cooling had multiple effects on regional climate. HP Pavilion dv6-2150us laptop keyboard
This lack of monsoon caused extensive rainfall over the Sahara desert, expansion of the Thar desert, more dust deposited into the Arabian Sea, and a lowering of the biotic life zones on the Indian subcontinent. Animals responded to this shift in climate, with the Javan Rusa deer migrating into India.[21] HP Pavilion dv6-2030ev laptop keyboard
In addition, the glaciers in Tibet created meltwater lakes in the Qaidam Basin, the Tarim Basin and the Gobi Desert, despite the strong evaporation caused by the low latitude. Silt and clay from the glaciers accumulated in these lakes: when the lakes dried at the end of the ice age, TOSHIBA Satellite L655-S5083 laptop keyboard
the silt and clay were blown by the downslope wind off the Plateau. These airborne fine grains produced the enormous amount of loess in the Chinese lowlands.[21]
Since the end of the ice age, TOSHIBA Satellite L655-S5160 laptop keyboard
Tibet has risen at approximately 10 millimetres (0.39 in) per year, at the same rate as the Himalaya. While the Himalaya rise can be explained by plate tectonics, Lenovo 3000 G430 4152 laptop keyboard
the rise of Tibet can be explained as the isostatic rebound of the crust rising after the weight of the ice was removed. The amount of isostatic rebound since the last ice age is approximately 650 metres (2,130 ft).[19] Packard Bell Easynote TK85 laptop keyboard
The Tibetan Plateau contains the world's third-largest store of ice. Qin Dahe, the former head of the China Meteorological Administration, said that the recent fast pace of melting and warmer temperatures will be good for agriculture and tourism in the short term; but issued a strong warning: Acer eMachines E640 laptop keyboard
"Temperatures are rising four times faster than elsewhere in China, and the Tibetan glaciers are retreating at a higher speed than in any other part of the world." "In the short term, TOSHIBA Satellite L200 laptop keyboard
this will cause lakes to expand and bring floods and mudflows." "In the long run, the glaciers are vital lifelines for Asian rivers, including the Indus and the Ganges. Once they vanish, water supplies in those regions will be in peril."[22] TOSHIBA NSK-TK001 laptop keyboard
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