Explain the formation of Indian monsoons. Highlight the link between monsoons and India’s cropping pattern. (15 marks)

Mentor’s Comment:

The similar question has been asked in UPSC. ‘What characteristics can be assigned to monsoon climate that succeeds in feeding more than 50 percent of the won population residing in Monsoon Asia?’ (UPSC Mains 2017).

Introduction should explain monsoon as a global phenomena influenced by variety of factors affecting pattern of rainfall in Indian subcontinent.

Next point should explain about the formation of Indian Monsoon. Like seasonal winds which reverse their direction with the change of season, convection cell on a very large scale, formed due to intense pressure (low/high) over Tibetan Plateau, the zone of ITCZ and its shifting, heavy rainfall with ascending cloud etc.

Further mention about India’s cropping pattern linked to Monsoon. Indian economy is heavily dependent on agriculture which is dependent on Monsoon, rabi and kharif crop and their growing season which is dependent on on-setting and offsetting of monsoon, delay monsoon delay cropping pattern. Bring examples of crops.

Conclude based on the points of main body.

Model Answers:

Although the monsoon is a global phenomenon influenced by a variety of factors not yet completely understood, the real monsoon rains cover mainly the South Asian region, represented by India, Myanmar, Sri Lanka, Bangladesh, Bhutan and parts of Southeast Asia. The monsoon system of the Indian subcontinent differs considerably from that of the rest of Asia. The centres of action, air masses involved, and the mechanism of precipitation of the Indian monsoon are altogether different from other monsoon systems.

Formation of Indian Monsoon:

  • Monsoons are seasonal winds (Rhythmic wind movements or Periodic Winds) which reverse their direction with the change of season.
  • The monsoon is a double system of seasonal winds – They flow from sea to land during the summer and from land to sea during winter.
  • Indian Monsoons are Convection cells on a very large scale.
  • India receives south-west monsoon winds in summer and north-east monsoon winds in winter.
  • South-west monsoons are formed due to intense low pressure system formed over the Tibetan plateau.
  • North-east monsoons are associated with high pressure cells over Tibetan and Siberian plateaus.

  • The southeast trade winds in the southern hemisphere and the northeast trade winds in the northern hemisphere meet each other near the equator.
  • The meeting place of these winds is known as the Inter-Tropical Convergence Zone (ITCZ).
  • This is the region of ascending air, maximum clouds and heavy rainfall.
  • The location of ITCZ shifts north and south of equator with the change of season.
  • In the summer season, the sun shines vertically over the Tropic of Cancer and the ITCZ shifts northwards.
  • The southeast trade winds of the southern hemisphere cross the equator and start blowing in southwest to northeast direction under the influence of Coriolis force.
  • These displaced trade winds are called south-west monsoons when they blow over the Indian subcontinent.
  • The front where the south-west monsoons meet the north-east trade winds is known as the Monsoon Front. Rainfall occurs along this front.
  • In the month of July, the ITCZ shifts to 20°- 25° N latitude and is located in the Indo-Gangetic Plain and the south-west monsoons blow from the Arabian Sea and the Bay of Bengal.
  • The ITCZ in this position is often called the Monsoon Trough (maximum rainfall).
  • The seasonal shift of the ITCZ has given the concept of Northern Inter-Tropical Convergence Zone (NITCZ) in summer (July – rainy season) and Southern Inter-Tropical Convergence Zone (SITCZ) in winter (Jan – dry season).
  • NITCZ is the zone of clouds and heavy rainfall that effects India.
  • In normal circumstances, when the tropical eastern South Pacific Ocean experiences high pressure, the tropical eastern Indian Ocean experiences low pressure. Such changes in the pressure conditions over the southern oceans also affect the monsoon.

  • But in certain years, there is a reversal in the pressure conditions. In this case, the eastern Pacific Ocean has lower pressure compared to the eastern Indian Ocean. This periodic change in pressure conditions is known as the Southern Oscillation or SO.

Monsoon and India’s cropping pattern:

  • The Indian economy is heavily dependent on agriculture and the livelihood of the Indian farmer largely depends on the Monsoon rains.
  • The agricultural crop year in India is from July to June.
  • The Indian cropping season is classified into two main seasons-(i) Kharif and (ii) Rabi based on the monsoon.
  • The kharif cropping season is from July –October during the south-west monsoon and the Rabi cropping season is from October-March (winter).
  • The crops grown between March and June are summer crops.
  • The kharif crops include rice, maize, bajra, cereals), arhar, soybean, groundnut etc.
  • The rabi crops include wheat, barley, oats , chickpea, mustard etc.
  • Rainfed agriculture still accounts for over 92.8 million hectares or 65 percent of the cropped area.
  • A large diversity of cropping systems exists under rainfed and dryland areas with an overriding practice of intercropping, due to greater risks involved in cultivating larger area under a particular crop.
  • Those areas of India where monsoon activities are less, the cropping patterns are less diversified.
  • For instance, in the rainfall scarce areas of Rajasthan (India), the farmers grow bajra (bulrush millet), while in the Brahmaputra valley of Assam, which is rain abundant area, rice is the dominant crop while other crops coexist.
  • Likewise, cotton is grown in Maharashtra and Gujarat which gets less rain, while the moisture rich soils of western Uttar Pradesh, Haryana and Punjab are ideally suited for wheat, rice and sugarcane crops because they get proper monsoon..
  • If in a certain year, the monsoon is delayed, then the cropping pattern changes in favour of short-duration crops like pulses.
  • Incessant rains in some parts of the country, and deficit rains in other areas, results in inconsistent agriculture spread and crop damage in certain locations.
  • The pattern of an area sown is completely guided by the variation in the monsoon season as a bad monsoon directly impacts the cost of cultivation and makes sowing of large areas unprofitable for the farmers.

Although there are wide variations in weather patterns across India, the monsoon brings some unifying influences on India. The Indian landscape, its flora and fauna, etc. are highly influenced by the monsoon. The entire agricultural calendar in India is governed by the monsoon. Due to these reasons, monsoon is often a great unifying factor in India.