Mechanism of monsoon


 
 
Concept Explanation
 

Mechanism of monsoon

Mechanism of Monsoon: The following facts are important to understand the mechanism of the monsoons

  • The differential heating and cooling of land and water creates low pressure on the landmass of India while the seas around experience comparatively high pressure.
  • The Inter Tropical Convergence Zone (ITCZ) in summer season shifts its position over the Ganga plain. This is the equatorial trough normally positioned about 5°N of the equator. It is also known as the ‘monsoon trough’ during the monsoon season.
  •  The presence of the high-pressure area, East of Madagascar (approximately at 20°S over the Indian Ocean). The intensity and position of this high-pressure area affects the Indian monsoon.
  • The Tibetan plateau gets intensely heated during summer, which results in strong vertical air currents and the formation of low pressure over the plateau at about 9 km above sea level.
  • The movement of the westerly jet stream to the North of the Himalayas and the presence of the tropical Easterly jet stream over the Indian peninsula during summer.
  • Apart from the given facts, it has been noticed changes in the pressure conditions over the Southern oceans also affect the monsoons. Normally, when the tropical Eastern South Pacific Ocean experiences high pressure, the tropical Eastern Indian Ocean experiences low pressure.

    But in past a few years, there is a reversal in the pressure conditions and the Eastern Pacific has lower pressure in comparison to the Eastern Indian Ocean. This periodic change in pressure conditions is known as Southern Oscillation (SO).

    Sample Questions
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    Question : 1

    In which monsoon, the Sun shines vertically over the Tropic of Cancer resulting in high temperature and low pressure is still sufficiently high over Arabian Sea and Bay of Bengal?

    Right Option : B
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    Question : 2

    When the winds blow from North East to the South - West in winter from land to sea, it is called ______ monsoon in winter.

    Right Option : C
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    Question : 3

    Jetstreams blow south of the Himalayas all through the year except in _______________ season.

    Right Option : C
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