Michaung Wreaks Havoc: What Makes the Bay of Bengal a 'Hotbed' of Cyclones?

From high temperatures to inflow of warm river water, many factors make the Bay of Bengal 'unstable'.

Cyclone Michaung: While at least 12 people died amid extremely heavy rainfall in Chennai, a four-year-old boy lost his life in Andhra Pradesh's Tirupati district.

(Photo: PTI)

Michaung is the latest cyclone to have struck the Bay of Bengal, wreaking havoc in Tamil Nadu and Andhra Pradesh.

While at least 12 people died amid extremely heavy rainfall in Chennai, a four-year-old boy lost his life in Andhra Pradesh's Tirupati district.

What are the reasons behind a large number of cyclones occurring in the Bay of Bengal? What makes it such a volatile area?

From high sea surface temperature to inflow of warm water from rivers, we explore the various reasons.

Depth & Geographical Factors

According to meteorologists, the most fertile area for cyclones to form tend to be shallow – and that's exactly what the Bay of Bengal is.

The Bay is more shallow than the Arabian Sea, and its larger surface area leads to faster heating, which causes faster evaporation. Faster evaporation thereby leads to a high-pressure zone being formed, which makes the region extremely unstable. All of these factors combined makes the area a hotbed for cyclonic formations.

The Bay is also characterised by high sea surface temperatures, which can trigger extremely destructive cyclones.

What further fuels the instability of the region is its geography. The Bay is surrounded by land on three sides, which adds to the moisture content. Low-lying areas, thus, are most at risk as they often get flooded when cyclones make landfall.

Moreover, the long and curved coastline of the Bay triggers high wind speeds, which leads to storms gaining greater intensity – thus adding fodder to its destructive capacity.

Bay of Bengal & Arabian Sea: A Comparison

The Bay of Bengal is far more prone to cyclones than the Arabian Sea. So much so that the Bay of Bengal has actually been known to cause "80 percent of the world's cyclone related deaths", as per The Weather Channel.

The Bay of Bengal gets more rainfall than the Arabian Sea, and warm air currents keep temperatures high during the entire year. The incessant inflow of fresh warm water from rivers like the Ganga and Brahmaputra also make it difficult for the water in the upper levels of the Bay to mix with cooler water in the lower levels.

On the other hand, the Arabian Sea is much calmer and strong winds blowing in the region dissipate heat. Further, the absence of fresh water inflow from rivers helps the warm water in the upper levels to mix with cooler water below, thus leading to a reduction of surface temperature.

Furthermore, winds from the Pacific Ocean get blocked by the Western Ghats and the Himalayas, thus reducing its intensity before they reach the Arabian Sea. Often the winds don't reach the Arabian Sea at all.

Michaung, Amphan, Yaas: The Monsters That Have Struck the Bay of Bengal

Several powerful cyclones have struck the Bay of Bengal in recent years.

Amphan, which made landfall in West Bengal in May 2020, was the most destructive cyclone to have struck the region since 1999. The severe storm led to the deaths of at least 98 people and caused damages to property and infrastructure to the amount of around $14 billion, according to officials.

Similarly, Cyclone Yaas made landfall in Odisha in May 2021 and impacted neighbouring West Bengal and Jharkhand as well. Fourteen people in total (Six in Odisha, four in West Bengal, and four in Jharkhand) died due to the cyclone.

Other powerful cyclones that have made landfall in the region include Aila (2009), Fani (2019), and Bulbul (2019).

There are a few other coastlines that are almost as vulnerable to cyclones as the Bay of Bengal is, like the Gulf Coast of Louisiana. However, "the north coast of the Bay of Bengal is more prone to catastrophic surges than anywhere on Earth," Meteorologist Bob Henson told the BBC.

As of 2020, a list maintained by Weather Underground states that 26 of the 35 deadliest tropical cyclones have occurred in the region.