Geography of Tibet

Source: Wikipedia, the free encyclopedia.
This article is about the geography of the ethno-cultural region of Tibet, which includes, but is not the same as the Tibet Autonomous Region of China. For the non-political geographical region, see Tibetan Plateau.
Yamdrok Lake

The geography of Tibet consists of the high mountains, lakes and rivers lying between Central, East and South Asia. Traditionally, Western (European and American) sources have regarded Tibet as being in Central Asia, though today's maps show a trend toward considering all of modern China, including Tibet, to be part of East Asia.[1][2][3] Tibet is often called "the roof of the world," comprising tablelands averaging over 4,950 metres above the sea with peaks at 6,000 to 7,500 m, including Mount Everest, on the border with Nepal.

Description

It is bounded on the north and east by the

Himalaya
and many of the highest mountain peaks in the world.

High mountain peaks include

Mount Nyainqentanglha, Namcha Barwa, Shishapangma and Yangra
. Mountain passes include Cherko la and North Col. Smaller mountains include Mount Gephel and Gurla Mandhata.

Regions

Physically, Tibet may be divided into two parts, the "lake region" in the west and north-west, and the "river region", which spreads out on three sides of the former on the east, south, and west.

subtropical highland climate with moderate summer rainfall averaging around 500 millimetres (20 in) per year, and daytime temperatures ranging from around 7 °C (45 °F) in winter to 24 °C (75 °F) in summer – though nights are as much as 15 °C (27 °F) cooler. Rainfall decreases steadily to the west, reaching only 110 millimetres (4.3 in) at Leh on the edge of this region, whilst temperatures in winter become steadily colder. On the south the "river region" is bounded by the Himalayas, on the north by a broad mountain system. The system at no point narrows to a single range; generally there are three or four across its breadth. As a whole the system forms the watershed between rivers flowing to the Indian Ocean – the Indus, Brahmaputra and Salween and its tributaries – and the streams flowing into the undrained salt lakes to the north.[4]

The "river region" is characterized by fertile mountain valleys and includes the

Yarlung Tsangpo Canyon, formed by a horseshoe bend in the river where it flows around Namcha Barwa, is the deepest, and possibly longest canyon in the world.[6] Among the mountains there are many narrow valleys. The valleys of Lhasa, Shigatse, Gyantse and the Brahmaputra are free from permafrost, covered with good soil and groves of trees, well irrigated, and richly cultivated.[4]

The

Lake Paiku and Lake Puma Yumco
.

The "lake region" extends from the

discontinuous permafrost over the Chang Tang, the soil is boggy and covered with tussocks of grass, thus resembling the Siberian tundra. Salt and fresh-water lakes are intermingled. The lakes are generally without outlet, or have only a small effluent. The deposits consist of soda, potash, borax and common salt. The lake region is noted for a vast number of hot springs, which are widely distributed between the Himalaya and 34° N., but are most numerous to the west of Tengri Nor (north-west of Lhasa). So intense is the cold in this part of Tibet that these springs are sometimes represented by columns of ice, the nearly boiling water having frozen in the act of ejection.[4]

Climate

The climate of Tibet is severely dry nine months of the year, and average annual snowfall is only 46 cm (18 inches), due to the rain shadow effect. Western passes receive small amounts of fresh snow each year but remain traversible all year round. Low temperatures are prevalent throughout these western regions, where bleak desolation is unrelieved by any vegetation bigger than a low bush, and where the wind sweeps unchecked across vast expanses of arid plain. The Indian monsoon exerts some influence on eastern Tibet. Northern Tibet is subject to high temperatures in the summer and intense cold in the winter.[4]

Climate data

Climate data for Lhasa (Köppen BSk/Dwb/Cwb)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °C (°F) 20.5
(68.9) 		21.3
(70.3) 		25.1
(77.2) 		25.9
(78.6) 		29.4
(84.9) 		30.8
(87.4) 		30.4
(86.7) 		27.2
(81.0) 		26.5
(79.7) 		24.8
(76.6) 		22.8
(73.0) 		20.1
(68.2) 		30.8
(87.4)
Mean daily maximum °C (°F) 8.4
(47.1) 		10.1
(50.2) 		13.3
(55.9) 		16.3
(61.3) 		20.5
(68.9) 		24.0
(75.2) 		23.3
(73.9) 		22.0
(71.6) 		20.7
(69.3) 		17.5
(63.5) 		12.9
(55.2) 		9.3
(48.7) 		16.5
(61.7)
Daily mean °C (°F) −0.3
(31.5) 		2.3
(36.1) 		5.9
(42.6) 		9.0
(48.2) 		13.1
(55.6) 		16.7
(62.1) 		16.5
(61.7) 		15.4
(59.7) 		13.8
(56.8) 		9.4
(48.9) 		3.8
(38.8) 		−0.1
(31.8) 		8.8
(47.8)
Mean daily minimum °C (°F) −7.4
(18.7) 		−4.7
(23.5) 		−0.8
(30.6) 		2.7
(36.9) 		6.8
(44.2) 		10.9
(51.6) 		11.4
(52.5) 		10.7
(51.3) 		8.9
(48.0) 		3.1
(37.6) 		−3
(27) 		−6.8
(19.8) 		2.7
(36.8)
Record low °C (°F) −16.5
(2.3) 		−15.4
(4.3) 		−13.6
(7.5) 		−8.1
(17.4) 		−2.7
(27.1) 		2.0
(35.6) 		4.5
(40.1) 		3.3
(37.9) 		0.3
(32.5) 		−7.2
(19.0) 		−11.2
(11.8) 		−16.1
(3.0) 		−16.5
(2.3)
Average precipitation mm (inches) 0.9
(0.04) 		1.8
(0.07) 		2.9
(0.11) 		8.6
(0.34) 		28.4
(1.12) 		75.9
(2.99) 		129.6
(5.10) 		133.5
(5.26) 		66.7
(2.63) 		8.8
(0.35) 		0.9
(0.04) 		0.3
(0.01) 		458.3
(18.06)
Average precipitation days (≥ 0.1 mm) 0.6 1.2 2.1 5.4 9.0 14.0 19.4 19.9 14.6 4.1 0.6 0.4 91.3
Average
relative humidity
(%) 		26 25 27 36 41 48 59 63 59 45 34 29 41
Mean monthly sunshine hours 250.9 231.2 253.2 248.8 280.4 260.7 227.0 214.3 232.7 280.3 267.1 257.2 3,003.8
Percent possible sunshine 78 72 66 65 66 61 53 54 62 80 84 82 67
Source 1: China Meteorological Administration,[9] all-time extreme temperature[10][11]
Source 2: China Meteorological Administration National Meteorological Information Center
Climate data for Shigatse (Köppen Dwb)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Mean daily maximum °C (°F) 5.6
(42.1) 		7.9
(46.2) 		10.9
(51.6) 		15.2
(59.4) 		18.9
(66.0) 		22.2
(72.0) 		20.8
(69.4) 		19.7
(67.5) 		18.5
(65.3) 		15.1
(59.2) 		10.3
(50.5) 		6.8
(44.2) 		14.3
(57.8)
Daily mean °C (°F) −3.7
(25.3) 		−0.8
(30.6) 		2.8
(37.0) 		7.3
(45.1) 		11.0
(51.8) 		14.9
(58.8) 		14.7
(58.5) 		13.9
(57.0) 		12.1
(53.8) 		6.9
(44.4) 		1.0
(33.8) 		−2.7
(27.1) 		6.5
(43.6)
Mean daily minimum °C (°F) −13.0
(8.6) 		−9.4
(15.1) 		−5.3
(22.5) 		−0.7
(30.7) 		3.2
(37.8) 		7.6
(45.7) 		8.7
(47.7) 		8.1
(46.6) 		5.7
(42.3) 		−1.2
(29.8) 		−8.3
(17.1) 		−12.2
(10.0) 		−1.4
(29.5)
Average precipitation mm (inches) 0
(0) 		0
(0) 		2
(0.1) 		3
(0.1) 		15
(0.6) 		60
(2.4) 		129
(5.1) 		146
(5.7) 		58
(2.3) 		7
(0.3) 		2
(0.1) 		0
(0) 		422
(16.7)
Source: Climate-Data.org [12]
Climate data for
Leh, India
(Köppen BWk)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °C (°F) 8.3
(46.9) 		12.8
(55.0) 		19.4
(66.9) 		23.9
(75.0) 		28.9
(84.0) 		34.8
(94.6) 		34.0
(93.2) 		34.2
(93.6) 		30.6
(87.1) 		25.6
(78.1) 		20.0
(68.0) 		12.8
(55.0) 		34.8
(94.6)
Mean daily maximum °C (°F) −2.0
(28.4) 		1.5
(34.7) 		6.5
(43.7) 		12.3
(54.1) 		16.2
(61.2) 		21.8
(71.2) 		25.0
(77.0) 		25.3
(77.5) 		21.7
(71.1) 		14.6
(58.3) 		7.9
(46.2) 		2.3
(36.1) 		12.8
(55.0)
Mean daily minimum °C (°F) −14.4
(6.1) 		−11.0
(12.2) 		−5.9
(21.4) 		−1.1
(30.0) 		3.2
(37.8) 		7.4
(45.3) 		10.5
(50.9) 		10.0
(50.0) 		5.8
(42.4) 		−1.0
(30.2) 		−6.7
(19.9) 		−11.8
(10.8) 		−1.3
(29.7)
Record low °C (°F) −28.3
(−18.9) 		−26.4
(−15.5) 		−19.4
(−2.9) 		−12.8
(9.0) 		−4.4
(24.1) 		−1.1
(30.0) 		0.6
(33.1) 		1.5
(34.7) 		−4.4
(24.1) 		−8.5
(16.7) 		−17.5
(0.5) 		−25.6
(−14.1) 		−28.3
(−18.9)
Average rainfall mm (inches) 9.5
(0.37) 		8.1
(0.32) 		11.0
(0.43) 		9.1
(0.36) 		9.0
(0.35) 		3.5
(0.14) 		15.2
(0.60) 		15.4
(0.61) 		9.0
(0.35) 		7.5
(0.30) 		3.6
(0.14) 		4.6
(0.18) 		105.5
(4.15)
Average rainy days 1.3 1.1 1.3 1.0 1.1 0.4 2.1 1.9 1.2 0.4 0.5 0.7 13.0
Average
relative humidity (%) (at 17:30 IST
) 		51 51 46 36 30 26 33 34 31 27 40 46 38
Source: India Meteorological Department[13][14]

The effects of climate change

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:

"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, 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."[15]

Tibet during the last glacial period

Today Tibet is the most essential heating surface of the atmosphere. During the

Last glacial period a c. 2,400,000 square kilometres (930,000 sq mi) ice sheet covered the plateau.[16] This glaciation took place in correspondence to a lowering of the snowline by 1,200 metres (3,900 ft). For the Last Glacial Maximum
this means a depression of the average annual temperature by 7 to 8 °C (13 to 14 °F) at a minor precipitation compared with that one of today.

Owing to this drop in temperature a supposed drier climate has partly been compensated with regard to the glacier feeding by a minor evaporation and an increased relative humidity. Due to its great extension this glaciation in the subtropics was the most important climatically foreign element on earth. With an albedo about 80-90% this ice area of Tibet has reflected an at least 4 times greater global radiation energy per surface into space than the further inland ices at a higher geographical latitude. At that time the most essential heating surface of the atmosphere – which at present, i.e. interglacially, is the Tibetan plateau – was the most important cooling surface.[17]

The annual low-pressure area induced by heat above Tibet as a motor of the summer

Javan Rusa
far into South Asia are a consequence of this glaciation.

Despite heavy

insolation, the discharge of the glaciers into the Inner-Asian basins was sufficient for the creation of meltwater lakes in the Qaidam Basin, the Tarim Basin and the Gobi Desert. The drop in temperature (see above) was in favour of their development. Thus, the clay fraction produced by the ground scouring of the important glaciation was ready to be blown-out. The blow-out of the limnites and the Aeolian long-distance transport were connected to the katabatic winds. Accordingly, the Tibetan glaciation was the actual cause of the enormous loess production and the transport of the material into the Chinese middle- and lowlands continuing to the east.[18]
During the Ice Age the katabatic air current – the name 'winter monsoon' is not quite correct – blew all year round.

The enormous uplift of Tibet by around 10 mm/year measured by triangulations since the 19th century and confirmed by glaciogemorphological findings as well as by seismological investigations equals the uplift of the Himalaya. However, these amounts of uplift are far too important as to a primarily tectonic uplift of the high plateau which only takes place epirogenetically. Actually they can be understood the better by a superimposed glacioisostatic compensation movement of Tibet about 650 m.[19]

An alternative view held by some scientists[20] is that the glaciers on the Tibetan Plateau have remained restricted over the entire data published since 1974 in the literature referred to in Kuhle (2004),[21] which are relevant as to the maximum ice extent.

  • Himalayas near Lhasa
    Himalayas near Lhasa
  • Tibet is located on the Tibetan Plateau, the world's highest region.
    Tibet is located on the Tibetan Plateau, the world's highest region.
  • Tibetan Plateau and surrounding areas above 1600-m topography[22][23]
    Tibetan Plateau and surrounding areas above 1600-m topography[22][23]
  • The Tibetan plateau lies between the Himalayan range to the south and the Taklamakan plain to the north.
    The Tibetan plateau lies between the
    Taklamakan
    plain to the north.
  • Lake Pangong Tso
    Lake Pangong Tso
  • Glacier-capped mountains in Tibet
    Glacier-capped mountains in Tibet
  • Animation of glacier-capped mountains in Tibet

See also

Wikimedia Commons has media related to Geography of Tibet.

Notes

  1. ^ "plateaus". Archived from the original on January 11, 2008.
  2. ^ "East Asia Region".
  3. ^ "UNESCO Collection of History of Civilizations of Central Asia Volume IV". Retrieved 2009-02-19.
  4. ^ a b c d e Waddell & Holdich 1911, p. 917.
  5. ^ "Tibet: Agricultural Regions". Archived from the original on 2007-08-24. Retrieved 2007-08-06.
  6. ^ "The World's Biggest Canyon". www.china.org. Retrieved 2007-06-29.
  7. ISBN 7-5085-0665-0
    .
  8. ISBN 0-7923-6688-3
    , p. 312;
  9. ^ 中国地面国际交换站气候标准值月值数据集（1971－2000年） (in Chinese). China Meteorological Administration. Archived from the original on October 16, 2013. Retrieved 2010-05-04.
  10. ^ "Extreme Temperatures Around the World". Retrieved 2013-02-21.
  11. ^ "55591: Lhasa (China)". ogimet.com. OGIMET. 28 March 2022. Retrieved 29 March 2022.
  12. ^ "Climate: Shigatse - Climate-Data.org". Archived from the original on 22 January 2018. Retrieved 21 January 2018.
  13. ^ "Leh Climatological Table Period: 1951–1980". India Meteorological Department. Archived from the original on 25 February 2018. Retrieved April 11, 2015.
  14. ^ "Leh Climatological Table Period: 1951–1980". India Meteorological Department. Archived from the original on 21 July 2011. Retrieved April 4, 2020.
  15. ^ Global warming benefits to Tibet: Chinese official. Reported 18/Aug/2009.
  16. ^ Matthias Kuhle (1997): New Findings concerning the Ice Age (Last Glacial Maximum) Glacier Cover of the East-Pamir, of the Nanga Parbat up to the Central Himalaya and of Tibet, as well as the Age of the Tibetan Inland Ice. GeoJournal 42 (2-3, Tibet and High Asia IV. Results of Investigations into High Mountain Geomorphology, Paleo- Glaciology and Climatology of the Pleistocene (Ice Age Research)), 87-257.
  17. ^ Matthias Kuhle (2011): Ice Age Development Theory. In: Encyclopedia of Snow, Ice and Glaciers. Eds: V. P. Singh, P. Singh, U. K. Haritashya, 576-581, Springer.
  18. ^ Matthias Kuhle (2001): The Tibetan Ice Sheet; its Impact on the Palaeomonsoon and Relation to the Earth's Orbital Variations. Polarforschung 71 (1/2), 1-13.
  19. ^ Matthias Kuhle (1995): Glacial Isostatic Uplift of Tibet as a Consequence of a Former Ice Sheet. GeoJournal 37 (4), 431-449.
  20. ^ Lehmkuhl, F., Owen, L.A. (2005): Late Quaternary glaciation of Tibet and the bordering mountains: a review. Boreas, 34, 87-100.
  21. ^ Matthias Kuhle (2004): The High Glacial (Last Ice Age and LGM) ice cover in High and Central Asia. Development in Quaternary Science 2c (Quaternary Glaciation - Extent and Chronology, Part III: South America, Asia, Africa, Australia, Antarctica, Eds: Ehlers, J.; Gibbard, P.L.), 175-199.
  22. ^ National Geophysical Data Center, 1999. Global Land One-kilometer Base Elevation (GLOBE) v.1. Hastings, D. and P.K. Dunbar. National Geophysical Data Center, NOAA. doi:10.7289/V52R3PMS [access date: 2015-03-16]
  23. ^ Amante, C. and B.W. Eakins, 2009. ETOPO1 1 Arc-Minute Global Relief Model: Procedures, Data Sources and Analysis. NOAA Technical Memorandum NESDIS NGDC-24. National Geophysical Data Center, NOAA. doi:10.7289/V5C8276M [access date: 2015-03-18].

References

External links
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