Out of five cyclones that the Indian coastline witnessed in a year, four originated in the Bay of Bengal and only one in the Arabian Sea.
Year after year the eastern coastal belt of India has been ravaged by super cyclonic storms. After Amphan’s destructive tryst on May 20 last year, cyclone Yaas is making landfall in Odisha. Just a week back cyclone Tauktae that originated in the Arabian sea claimed lives in Maharashtra and Gujarat. Nevertheless, the Bay of Bengal is a more active basin than the Arabian Sea for brewing cyclonic storms.
In the last four years 12 cyclones have formed in the Bay and ravaged the Eastern coastal states of India. Out of five cyclones that the Indian coastline witnessed in a year, four originated in the Bay of Bengal and only one in the Arabian Sea.
Dr Harsh Vardhan, Minister for Science and Technology and Earth Sciences has also drawn attention to the increasing frequency of cyclone formation in the North Indian Ocean in recent years.
Why Bay of Bengal is the hot-bed for cyclonic storms
Cyclones in the Bay of Bengal can be attributed to the vast low pressure created by the warm water of the ocean. Meteorologists believe the bay that gives birth to severe cyclones is concave or shallow where when strong winds push water, it gets concentrated as a storm. The Bay of Bengal shaped like a trough that makes it more hospitable for storms to gain force. Moreover, the high sea surface temperature makes matters more worse in the Bay triggering the intensity of the storms.
Additionally, the Bay of Bengal gets more rainfall with sluggish winds and warm air currents around it that keep temperatures relatively high all year. The constant inflow of fresh warm water from the perineal rivers like Bramhaputra, Ganga makes it further impossible to mix with the cooler water below. Lack of landmass between the Pacific Ocean and the Bay of Bengal tend cyclonic winds to move into the coastal areas causing heavy rainfall. The absence of air movements from north-western India towards the Bay in the post-monsoon phase is also another reason for the chances of cyclones in the Bay of Bengal.
What geographical advantage the Arabian sea has
As for the the Arabian Sea, it is much calm as the stronger winds help dissipate the heat and lack of constant fresh water helps the warm water to mix with the cool water underneath, reducing the surface temperature. The Arabian Sea enjoys the locational advantage as the winds from the Pacific Ocean encounter the Western Ghats and the Himalayas cutting down on its intensity and sometimes never reaching the Arabian Sea.
The most devastating cyclone in Bengal so far was Bhola in 1970 where five lakh people were killed in erstwhile East Pakistan and West Bengal. In recent time, Nargis which hit Myanmar in 2008 claimed more than 1 lakh, 40 thousand lives.