Why do so many cyclones form over the Bay of Bengal?

The region, which occupies just 0.6% of the global ocean area, is estimated to be responsible for four out of five cyclone-related deaths in the world.

 |  4-minute read |   09-05-2022
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The Bay of Bengal is witnessing another cyclone. After intensifying into a severe cyclonic storm, Cyclone Asani is approaching the Odisha-Andhra Pradesh coast, where it will bring heavy rain over the next two days.

The Bay of Bengal has always been a cyclone hotbed. Eight out of ten deadliest tropical cyclones in the world have originated over this region.



It's been 22 years since Odisha was battered by a Super Cyclonic Storm on 29th October, 1999, which resulted in death of nearly 10,000 people.

Since then, India has made great progress and death numbers have reduced significantly.

We take a look at major cyclones that have hit the Bay of Bengal, areas that are more prone to cyclonic storms and what has changed over the years.


As many as 117 cyclones hit India in 50 years from 1970-2019 claiming over 4 lakh lives, according to a study on extreme weather events, reported PTI.

A total of 7,063 extreme weather events killed 1,41,308 people during the period in the country, which included 40,358 (or 28 per cent) due to cyclones and 65,130 (a little over 46 per cent) due to floods, the study says.



BHOLA CYCLONE, 1970: On November 11, 1970, the Great Bhola Cyclone hit the coasts of East Pakistan (now Bangladesh) and killed 3 lakh to 5 lakh people. It is the deadliest known cyclone till date. Over 45 per cent of the population of one lakh 67 thousand in the city of Tazumuddin was killed, according to the University of Rhode Island. The maximum storm surge was estimated at nearly 35 feet high, causing massive destruction. 

ODISHA SUPER CYCLONE, 1999: One of the most severe tropical cyclones to hit India in the last few decades was the 1999 Odisha Cyclone. The Category 4-equivalent storm with 155-mph winds struck Odisha's coast on October 29, 1999. The cyclonic storm pushed a storm surge of 26 feet (8 meters) and killed an estimated 10,000 people. More than 3.5 lakh houses were destroyed, several villages were completely washed away. So bad was the damage to Odisha's infrastructure that the state went out of contact with the rest of the world for an entire day, reported India Today.

odisha_050922031409.jpgPhoto: India Today Archives

CYCLONE NARGIS, 2008: Cyclone Nargis passed over Myanmar after having formed in the Bay of Bengal. The Category 3/4 storm carried very powerful winds and heavy rains as it devastated the southern delta region of Myanmar, southeast of Bangladesh. More than 130,000 people were killed making it one of the worst cyclones in the last few decades, reported Weather.com.


The Bay of Bengal, which occupies just 0.6% of the global ocean area, is estimated to be responsible for four out of five cyclone-related deaths in the world, reported Weather.com. Over the past two centuries, 42% of the cyclone-associated deaths of nearly 20 lakh have occurred in Bangladesh alone.

According to an IMD report, Sundarbans is the cyclone capital of India;  and West Bengal’s South 24 Parganas district, within which the larger share of the Indian Sundarbans is located, is impacted by cyclones the most frequently, reported DownToEarth magazine.

sorrow_050922034733.jpgPhoto: Getty Images


The unusually high number of deaths due to cyclones in Bay of Bengal can also be attributed to the triangular shape of the bay, which acts as a funnel and causes massive storm surges. As the shallow bottom of the bay allows further surge, the low-lying areas of the coastal regions often get inundated, said a report in Weather.com.


Timely warnings, setting up of disaster relief teams and a better evacuation process have been some of the main reasons India has been able to significantly reduce the death toll due to cyclones. 

The "zero casualty policy” for cyclones and the pinpoint accuracy of the India Meteorological Department (IMD) has also played a key role in better management of cyclones.


ISRO has also contributed significantly to India’s cyclone management system. Space-based systems have become the primary tools for collecting data on cyclones. 

Since the 1999 cyclone in Odisha, which claimed over 10,000 lives, casualties have been limited to double figures in most cases. 

The mortality rate associated with cyclones decreased by almost 88 per cent from 2010-2019 in comparison to the earlier decade (2000-2009), reported PTI.



Vivek Mishra Vivek Mishra @vvk29

Vivek likes to follow politics, international affairs, sports and technology. He is currently an Assistant Editor at DailyO.

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