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Recent Theory of Origin and Mechanism of Monsoon UPSC | Geography of India| UPSC | UP-PCS | State PCS

Recent Theory of Origin and Mechanism of Monsoon UPSC | Geography of India| UPSC | UP-PCS | State PCS

07:53

No single theory, whether it is the old theory (thermal theory) or the modern theory (jet stream or air force theory) is not able to fully explain the origin and mechanism of monsoon.


The origin and mechanism of monsoon are very complex and are not yet fully understood. The origin and mechanism of the Indian monsoon are responsible for its variable and unpredictable nature.

Modern theories try to explain the origin and mechanism of monsoons by analyzing all the factors that influence monsoons.

The following are some of the important factors that are responsible for the origin of the Indian monsoon and the mechanism responsible for its variable and unpredictable nature:

Role of relief, mountain, and plateau
  • Role of the Himalayas and Tibetan Plateau
  • Arakan mountain

Role of atmospheric factor
  • Role of ITCZ
  • the subtropical western jet stream
  • the tropical eastern jet stream
  • The high-pressure area east of Madagascar

Role of oceanic factor
  • El Nino
  • Na Nina
  • Oceanic Nino Index (ONI)
  • Southern Oscillation (SO)
  • SOI - Southern Oscillation Index
  • ENSO – El Nio Southern Oscillation
  • Indian Ocean Dipole-IOD
Relief and Mountains

Role of the Himalayas:

  • The Western Himalayas act as a barrier for the further northward movement of the moisture-laden southwest monsoon and prevent dry air from entering India from the north.
  • The warming of the Tibetan plateau attracts the humid airmass of the Indian Ocean toward the Indian subcontinent.
Role of Arakan Mountains
  • The Bay of Bengal branch of the monsoon enters Bangladesh and reaches Arakan mountain; the Arakan mountain deflects the bay of Bengal branch of the monsoon toward the Himalayas.
  • Himalayan splits this branch into two other branches:
  • The first branch moves towards the westward and northwestern directions reach to the Punjab plains and Haryana Plains which cause heavy rainfall in this region.
  • The second branch moves north and northeastern direction towards Assam plain causing heavy rainfall in the Meghalayan plateau and experiencing the world's highest rainfall in Mawsynram located in the Khasi hills.
Role of  Tibetan Plateau:
    • The temperature of the Tibetan plateau in summer is 2 to 3 degrees higher than the surrounding areas because the sun is near the Tropic of Cancer in the month of June, the Tibetan plateau is high ground and receives more insolation due to the clear sky.
      • Due to this, a low air pressure belt is formed here, due to which helps in attracting moist air from the oceans.
        • The eastern jet stream develops after the warming of the Tibetan Plateau in southern India and creates a tropical depression in India which helps in the distribution of monsoon over India.

        Atmospheric factors:
        Role of ITCZ:
        • It is the meeting point of two trade winds.
        • A convection current is formed in this region which helps in cloud formation.
        • When the ITCZ reaches the northern plains of India, the western jet stream which is over the northern plain moves north of the Himalayas, due to which the monsoon winds reach the Himalayas. 
        • Hence ITCZ causes the removal of the western jet stream from India which causes the burst of Monsoon in the Northern plains.

        Westerly subtropical Jet Stream:
        • The withdrawal of the Jet stream causes the burst of Monsoon in the Northern plains.
        The easterly tropical Jet stream:
        • The presence of the Easterly Jet stream helps to develop the depression zone over southern India that attracts moisture from the sea.

        High-pressure zone in the East of Madagascar:
        • The presence of a high-pressure zone in the East of Madagascar helps speed up moisture-laden air from the Arabian sea to the low-pressure area of the Indian continents. 
        Try to solve the following questions:
        • Are the origin and mechanism of the Indian monsoon responsible for its variable and unreliable nature? Discuss. ( 65th BPSC geography)
        • Discuss the major characteristics of the Indian monsoon with special emphasis on the causative factors( UPSC 1922)
        • Discuss the recent theories put forward to explain the origin and mechanism of the Indian Monsoon. ( UPSC, 1994)
        • Elucidate the mechanism of the Indian Monsoon( UPSC, 1999)
        • Explain the Origin, Mechanism, and characteristics of the Summer Monsoon in India. ( UPSC 2002)
        • Give a Critical account of the recent theories of the origin of the Indian monsoon with special reference to the Jet Stream Theory. (UPSC, 2006)
        • Discuss the mechanism and origin of Monsoon winds and explain the role of El Nino on Monsoon circulation. ( UPSC, 2008)
        • Discuss the mechanism of the Indian Monsoon (UPSC 2013)
        • Discuss the nature and origin of the Indian monsoon and recent techniques for its prediction. ( UPSC, 2014)
        • Give a reasonable account of the Unusual Pattern of Distribution of Monsoonal rainfall in India. ( UPSC, 2017)
        • Why is the monsoon erratic in nature? Explain. ( UPSC 2019)
        • Explain the origin, progress, and retreat of the Indian monsoon and discuss its impact on the Indian economy. (UPSC 2018, 250 words, 20 marks)
        • Elaborate on the origin of monsoon with reference to thermal and recent concepts. ( UPPSC 2020)

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