3.2.4.2 Tropical Monsoon Climate

•  Monsoon climate occurs mainly in India and Bangladesh.
• Temperature can average 30°C in the monsoon season and humidity is very high.
• Cyclones are frequent towards the end of the rainy season.
• Seasonal reversal of winds (determined by the annual movement of the Inter Tropical Convergence Zone).

  • Winter: They are from the north and north-east blowing outwards from Central Asia. These winds are very dry and there is a winter drought.
  • Summer: The winds reverse direction and blow from the south-west. Brings hot and wet air that originated over the equatorial area of the India Ocean. This causes large, intense amounts of rain that is increased by:
  • The uplift of air over the Western Ghats of south-west India and the foothills of the Himalayas.
  • Intense convection caused by hot land surface.
• Mumbai, India: Annual rainfall of 1811mm with all but 120mm falling in 4 months (June - September). Temperatures range from 30°C in Summer to 19°C in Winter.
• Rice seedlings: Grown in nurseries until the monsoon rains begin - transplanted into flooded fields (10-12 cm deep water).

  • These fields are level and have low mud walls to retain water.
  • Rice is best suited to lowland floodplains with deep fertile alluvial soils, however it can be grown in terraces cut into slopes of hilly areas (terrace farming).
  • India: Rice growing is mostly labour intensive - a large cheap labour force using simple tools and oxen does all the work.
• Indian economy gains due to good monsoon rains.

  • Can support large numbers of people in both rural areas and the rapidly growing cities of the Indo-Gangetic Plain.
  • Weak monsoon rains results in crop failure - negatively impacts the economy due to lower production. Can lead to rising prices, low industrial output etc.
  • There is a drive by the Indian government to increase the amount of land that is irrigated but it still stands at less than half the total land under cultivation.
• More than 4 billion people live in Asian countries that have monsoons.

  • Many areas in these countries do not have large irrigation systems but the summer monsoon rainfall fills aquifers and other groundwater stores for the rest of the year.
• Dairy farms (helps to make India the largest milk producer in the world) depends on monsoon rains to feed the cows.
• Industry and energy supplies are fed by the monsoon climate system e.g. India and SE Asia:

  • A large amount of electricity in the region is produced by hydroelectric power plants - driven by water collected from monsoons.
  • This electricity helps to power schools, hospitals and industry - vital to the local economy as the monsoon rain helps crops to grow.