Model Question and Answers for APSC | Tropical cyclones are largely confined to the South China Sea, Bay of Bengal and Gulf of Mexico. Why?

Ans: A tropical cyclone is a rapidly rotating storm originating over tropical oceans from where it draws the energy to develop. It has a low-pressure centre and clouds spiralling towards the eyewall surrounding the "eye", the central part of the system where the weather is normally calm and free of clouds.

Characteristics:

• Its diameter is typically around 200 to 500 km but can reach 1000 A tropical cyclone brings very violent winds, torrential rain, high waves and, in some cases, very destructive storm surges and coastal flooding.
• The winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern
• Tropical cyclones above a certain strength are given names in the interests of public

Different terminology is used for this weather phenomenon depending on the location:

• In the Caribbean Sea, the Gulf of Mexico, the North Atlantic Ocean and the eastern and central North Pacific Ocean, it is called "hurricane"
• In the western North Pacific, it is called "typhoon"
• In the Bay of Bengal and the Arabian Sea, it is called "cyclone"
• In the western South Pacific and the southeast Indian Ocean, it is called “severe tropical cyclone”
• In the southwest Indian Ocean, it is called a “tropical cyclone”

Largely confined to the South China Sea, Bay of Bengal and Gulf of Mexico:

• A tropical cyclone is sustained through the evaporation of water from the oceanic surface, which eventually results in the formation of clouds and rain which accompany a cyclone. Thus, the existence of a large and shallow water body is crucial to the formation of a tropical cyclone.

• This is also one of the reasons why tropical cyclones occur almost exclusively in the tropical shallow seas.
• The South China Sea, Bay of Bengal and Gulf of Mexico all fall in the Tropical zone, thus, increasing their suitability for the formation of tropical cyclones.
• Additionally, the requirement of warm sea surface temperatures is met only in tropical areas. Within the tropical regions themselves, tropical cyclones are commonly observed between the latitudes of 10 and 30 and not very near the equator.
• This is due to the fact that the Coriolis forces, which help the tropical cyclones rotate, is very weak near the
• Also, tropical cyclones typically form near the Intertropical Convergence Zone (ITCZ), which is the point of convergence of the northeast and southeast trade winds. The ITCZ is a very important component because it triggers the rotation of low-level winds which eventually develop into tropical cyclones.