From UPSC perspective, the following things are important :
Prelims level : Tropical cyclones
Mains level : Frequent landfalls of tropical cyclones in India
A developing cyclonic disturbance in the Bay of Bengal is expected to become a ‘severe cyclonic storm’ and make landfall in Tamil Nadu.
- The IMD has forecasted the development of a cyclone in the Southwest region of the Bay of Bengal, off Tamil Nadu coast.
- It has said that it will strengthen into a cyclone. Once intensified, it would acquire its name ‘Nivar’, proposed by Iran.
- After cyclone Gaja in 2018, this will be the second cyclone to cross Tamil Nadu in the last two years.
Try this PYQ:
In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason?
(a) Sea surface temperatures are low
(b) Inter-Tropical Convergence Zone seldom occurs
(c) Coriolis force is too weak
(d) Absence of land in those regions
- A Tropical cyclone is an intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain.
- Cyclones are formed over slightly warm ocean waters. The temperature of the top layer of the sea, up to a depth of about 60 meters, need to be at least 28°C to support the formation of a cyclone.
- This explains why the April-May and October-December periods are conducive for cyclones.
- Then, the low level of air above the waters needs to have an ‘anticlockwise’ rotation (in the northern hemisphere; clockwise in the southern hemisphere).
- During these periods, there is an ITCZ in the Bay of Bengal whose southern boundary experiences winds from west to east, while the northern boundary has winds flowing east to west.
- Once formed, cyclones in this area usually move northwest. As it travels over the sea, the cyclone gathers more moist air from the warm sea which adds to its heft.