Topic– Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc
1) The east coast of India is again going to be hit by a cyclone. Explain why Bay of Bengal is more prone to cyclones in India as compared to India’s west coast? Also explain, how are these cyclones classified?(250 words)
Why this question
Cyclone Titli is about to make landfall in India today and cause mayhem. The east coast of India is quite frequently ravaged by the destruction of such cyclones. Since this year, UPSC asked a lot of questions from the static section of all papers, we will make an attempt to cover the static portion of current happenings.
Key demand of the question
The question expects us to bring out the reasons why cyclones are more frequent on the east coast of India as compared to the west coast. Next, we need to explain how the categorisation of cyclones into severe, moderate etc is done.
Structure of the answer
Introduction – Link the static question to the current events, in this case landfall of Cyclone Titli.
- Evaluate the proposition that east coast of India receives more such cyclones as compared to west coast. Next, bring out the reasons for the same – Since sea surface temperatures and humidity both directly correlate with chances of cyclone formation, the Bay of Bengal is a more likely target because it gets higher rainfall, and because the sluggish winds around it keep temperatures relatively high: about 28 degrees around the year. Warm air currents enhance this surface temperature and aid the formation of cyclones. In addition, the Bay receives higher rainfall and constant inflow of fresh water from the Ganga and Brahmaputra rivers. This means that the Bay’s surface water keeps getting refreshed, making it impossible for the warm water to mix with the cooler water below, making it ideal for a depression. On the other hand, the Arabian Sea receives stronger winds that help dissipate the heat, and the lack of constant fresh water supply helps the warm water mix with the cool water, reducing the temperature.
- Also bring out that not all cyclones are formed in the Bay of Bengal. The basin is also host to cyclones that are formed elsewhere but move towards the water body, especially those formed in the Pacific Ocean. Cyclones usually weaken if they encounter a large landmass. However, due to the lack of any such presence between the Pacific and the Bay, cyclonic winds easily move into the Bay of Bengal. Once here, the winds encounter the Western Ghats and the Himalayas, either becoming weak or getting blocked in the Bay, but never reaching the Arabian Sea.
- Next, discuss how such cyclones are classified. Explain about the Saffir Simpson Wind Scale and how cyclones and hurricanes etc are classified.