1. Describe the physiographic features of the Tibetan plateau. How does the Tibetan plateau affect the weather pattern in the Indian subcontinent? Explain.
तिब्बती पठार की भौतिक विशेषताओं का वर्णन करें। भारतीय उपमहाद्वीप में तिब्बती पठार मौसम के मिजाज को कैसे प्रभावित करता है? समझाएं।
Demand of the question:
It expects students to give a clear account of the physiographic features of the Tibetan plateau. It also expects students to explain how does the Tibetan plateau affect weather pattern in the Indian subcontinent.
The Tibetan Plateau, also known as the Himalayan Plateau in India is a vast elevated plateau in Central Asia and East Asia, mostly covers parts of the India, Bhutan and China.
Physiographic features of the Tibetan plateau:
- Physiography of an area is the outcome of structure, process and the stage of development.
- The Tibetan Plateau is usually considered the largest and highest area ever to exist in the history of Earth. The plateau covers an area about half the size of the contiguous United States and averages more than 5,000 meters (16,400 feet) above sea level.
- The Tibetan Plateau is extremely important to the world’s water cycle because of its tremendous number of glaciers. These glaciers contain the largest volume of ice outside the poles.
- The Tibetan Plateau is surrounded by the massive mountain ranges of High-mountain Asia. The plateau is bordered to the south by the inner Himalayan range, to the north by the Kunlun Mountains, which separate it from the Tarim Basin, and to the northeast by the Qilian Mountains, which separate the plateau from the Hexi Corridor and Gobi Desert.
- The northern section of the plateau, called Qiangtang, is dotted with many brackish lakes; its southern section contains the headwaters of the upper Indus and Brahmaputra rivers.
- To the east and southeast the plateau gives way to the forested gorge and ridge geography of the mountainous headwaters of the Salween, Mekong, and Yangtze rivers in northwest Yunnan and western Sichuan (the Hengduan Mountains).
- In the west the curve of the rugged Karakoram range of northern Kashmir embraces the plateau. The Indus River originates in the western Tibetan Plateau in the vicinity of Lake Manasarovar.
- Other rivers that have their headwaters in the highlands are the Yangtze River (Chang Jiang), the Huang He (Yellow River), the Mekong, the Salween, and the Tarim.
- Grasslands are used for pasturage, and barley is grown on the plateau; forests grow on the slopes of valleys, particularly in the south.
- The most extensive farming in Tibet takes place on the fertile plains of the Brahmaputra River and its tributaries.
- Lhasa, the capital of Tibet, is the plateau’s major centre of population, economic activity, culture, and air and land transportation.
Tibetan plateaus effect on weather pattern in India Subcontinent:
- Monsoons are caused by the different amplitudes of surface temperature seasonal cycles between land and oceans. This differential warming occurs because heating rates differ between land and water.
- Tibetan plateau is an important heating surface of the atmosphere. Approximately 2,400,000 square kilometres (930,000 sq mi) ice sheet covered the plateau.
- Onset of the summer monsoon in the beginning of June is promoted by the hydrodynamic effect the Himalayas and not by the thermally induced low-pressure centre over northwest India.
- With a much lower latitude, the ice in Tibet reflects at least four times more radiation energy per unit area into space than ice at higher latitudes. Solar heating in late spring heats the Indian subcontinent, making it warmer than the Indian Ocean. It also warms the Tibetan plateau that acts as an elevated heat source. This drives southwest monsoon winds towards the Indian landmass.
- The snow-monsoon tele-connection works by altering this temperature gradient. There is dominant effect of the Himalaya and Tibetan plateau snow on monsoon is because of albedo, the reflectivity of snow. Increased snow cover over the Himalaya and Tibetan plateau reflects more solar radiation, resulting in less than normal warming of the land surface there. Consequently, the temperature gradient decreases and monsoon winds weaken. This means they bring less moisture to India and don’t penetrate as far north.
- The Tibetan plateau is the high level source of heat during summer time. During southwest monsoon, a thermal anticyclone appears over Tibet, which the resultant formation of dynamic anti-cyclogensis. On the south side of the anticyclone, the tropical jet stream is from.
- As a result, there is a sensible heat transfer from the elevated surfaces of the Himalayas and Tibet to the atmosphere. Besides this, large amounts of latent heat released by monsoon rains over India are also added to the upper troposphere anticyclone.
- Thus the presence of Tibet Highland is very important, as it helps for the onset of monsoon and helps to protect India from the northern cold winds.
The Tibetan plateau due to its distinct and unique physiographic features plays a vital role on the weather of Indian subcontinent and also has a geopolitical strategic significance as it is known as the “Rooftop of the World;” Hence, more study of this plateau can also help to tackle the emerging challenge of the global warming induced climate change.