Question

Discuss the mechanisms of the monsoon.

Answer 1

• While there is comparatively high pressure around the seas, the Indian landmass experiences low pressure due to differential cooling and heating of water and land.
• The other important mechanism of the monsoon is that, in summer over the plains of Ganga, the Inter Tropical Convergence Zone (ITCZ) will shift in its position. During the monsoon season, it is also known as the monsoon trough. It is positioned about 5°N of the equator and is also known as the equatorial trough.
• Over the Indian Ocean, around 20°S, towards the east of Madagascar, a high-pressure area is present.
• The Indian Monsoon is affected by the position and intensity of this high-pressure area.
• Above sea level, at about 9 Km, low pressure gets formed over the Tibetan plateau. This is the result of strong vertical air currents which are created due to the immense heat in the Tibetan plateau during the summer.
• Another very important mechanism of the monsoon is, over the Indian peninsula one can find the presence of the tropical easterly jet stream, and in the North of the Himalayas, one can find the movement of a westerly jet stream.
• Apart from the above-mentioned mechanisms which influence the monsoon, it has also been observed that over the southern oceans, the change in pressure conditions also has an effect on the monsoons.
• There is low pressure in the tropical eastern Indian Ocean when there is high pressure in the tropical eastern South Pacific Ocean.
• In some years, there will be a reversal of the situation i.e. eastern Indian Ocean will have a low-pressure situation in comparison to the pressure situation in the eastern Pacific Ocean.
• This pressure condition which keeps changing periodically is known as the Southern Oscillation.
• The intensity of the monsoon is predicted by computing the difference in pressure over Northern Australia (in Darwin) in the Indian Ocean and pressure conditions in the Pacific Ocean (over Tahiti).
• It can be concluded that the monsoon will be late and below average if the difference turns out to be negative.
• El Nino is connected to the changes in pressure conditions.
• Near the Peruvian Coast, a warm ocean current flows, which is known as the El Nino phenomenon and this feature has a connection with the Southern Oscillation (SO).