Formation of Tropical Cyclone – UPSC Notes/PDF

Tropical Cyclones are ferocious storms that originate over oceans in tropical areas and move over to the coastal areas causing violent winds, very heavy rainfall, and storm outpourings.

Tropical Cyclones are developed only in the ocean. There are two types of cyclones: (i) Tropical Cyclone and (ii) Temperate or extra-tropical cyclone. Temperate cyclone is developed between 35° and 65° latitude. Temperate cyclones are formed only on land.

The tropical cyclones developed between 8° to 20° latitudes. Some conditions need to satisfy for the formation of the tropical cyclone. They are:

  1. Large sea surface with a temperature higher than 27°C
  2. Presence of Coriolis force
  3. Small variations in the vertical wind speed
  4. A pre-existing weak low-pressure area

When the sea surface is heated and a low-pressure area is developed. The air starts rising.

The gap where the low-pressure area is developed is filled by surrounding high-pressure area and again it starts rising and forms cumulonimbus clouds hitting tropopause.

The air subsides at the centre of the low-pressure area. This area is called the ‘eye’ of the cyclone. The diameter of this eye may be as large as 65 km. (what?😮)

Around the eye is the eyewall, where there is a strong spiralling ascent of air to a greater height reaching the tropopause.

This system moves slowly about 300-500 km per day.

The diameter of the storm over the Bay of Bengal, the Arabian sea and the Indian ocean is between 600-1200 km.

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