Question

Write a note on the role of Tibetan plateau in the Indian monsoon.

Answer 1

Monsoons are seasonal winds which reverse their direction with the change of season.
Among several factors, Tibetan plateau plays a significant role in monsoon.
The summertime heating of the Plateau of Tibet was the most important factor in the causation and maintenance of the Monsoonal circulation. The Plateau of Tibet affects the atmosphere in two ways:

(i) Acting as a physical barrier
The vast mountain range also acted as a tall barrier, preventing cold, dry air in the northern latitudes from entering the subcontinent and subduing the warm, moisture-laden winds from the oceans that drives the monsoon.

(ii) Acting as a high-level heat source.
The summer time heating of the Tibetan Plateau makes it a high-level heat source. This heat engine produces a thermal anticyclone over this region during summer in the middle part of the troposphere. Winds coming out of this anticyclone in a clockwise movement over plateau give birth to easterly jet streams which flow from East to West on the southern side of this upper air anticyclone.

These upper air easterlies descend into the permanent high pressure area formed over the southern Indian Ocean and intensifies the high pressure area already present there. It is from this high-pressure cell that the onshore winds start blowing towards the thermally induced low-pressure area, developed in the northern part of the Indian subcontinent. After crossing the equator these surface winds change direction and become South- West monsoon.