Syllabus: General Studies Paper 1

Cyclone Asani, has developed over southeast regions of Bay of Bengal

How the cyclones are named and what are the guidelines on adopting their names?

• In 2000, a group of nations called WMO/ESCAP (World Meteorological Organisation/United Nations Economic and Social Commission for Asia and the Pacific), which comprised Bangladesh, India, the Maldives, Myanmar, Oman, Pakistan, Sri Lanka and Thailand, decided to start naming cyclones in the region.
• After each country sent in suggestions, the WMO/ESCAP Panel on Tropical Cyclones (PTC) finalised the list.
• The WMO/ESCAP expanded to include five more countries in 2018 — Iran, Qatar, Saudi Arabia, United Arab Emirates and Yemen.
• The list of 169 cyclone names released by IMD in April 2020 were provided by these countries — 13 suggestions from each of the 13 countries.

Why is it important to name cyclones?

• Adopting names for cyclones makes it easier for people to remember
• With a name, it is also easy to identify individual cyclones, create awareness of its development, rapidly disseminate warnings to increase community preparedness and remove confusion where there are multiple cyclonic systems over a region.

What are the guidelines to adopt names of cyclones?

While picking names for cyclones, countries need to follow some rules.

• The proposed name should be neutral to (a) politics and political figures (b) religious believes, (c) cultures and (d) gender
• Name should be chosen in such a way that it does not hurt the sentiments of any group of population over the globe
• It should not be very rude and cruel in nature
• It should be short, easy to pronounce and should not be offensive to any member
• The maximum length of the name will be eight letters
• The proposed name should be provided with its pronunciation and voice over
• The names of tropical cyclones over the north Indian Ocean will not be repeated. Once used, it will cease to be used again. 

Tropical Cyclone

Tropical cyclones are intense low-pressure areas confined to the area lying between 30° N and 30° S latitudes, in the atmosphere around which high velocity winds blow. Horizontally, it extends up to 500-1,000 km and vertically from surface to 12-14 km. A tropical cyclone or hurricane is like a heat engine that is energised by the release of latent heat on account of the condensation of moisture that the wind gathers after moving over the oceans and seas.

There are differences of opinion among scientists about the exact mechanism of a tropical cyclone. However, some initial conditions for the emergence of a tropical cyclone are:

1. Large and continuous supply of warm and moist air that can release enormous latent heat.
2. Strong Coriolis force that can prevent filling of low pressure at the centre (absence of Coriolis force near the equator prohibits the formation of tropical cyclone between 0°-5° latitude).
3. Unstable condition through the troposphere that creates local disturbances around which a cyclone develops.
4. Finally, absence of strong vertical wind wedge, which disturbs the vertical transport of latent heat.

Spatio-Temporal Distribution of Tropical Cyclone in India

Owing to its Peninsular shape surrounded by the Bay of Bengal in the east and the Arabian Sea in the west, the tropical cyclones in India also originate in these two important locations. Though most of the cyclones originate between 10°-15° north latitudes during the monsoon season, yet in case of the Bay of Bengal, cyclones mostly develop during the months of October and November. Here, they originate between 16°-2° N latitudes and to the west of 92° E. By July the place of origin of these storms shifts to around 18° N latitude and west of 90°E near the Sundarbans Delta.