Cyclone Mocha is expected to make landfall on Sunday. (file)
Yangon, Myanmar:
Five facts about tropical cyclones and storms ahead of powerful cyclone Mocha, which is expected to hit Myanmar and Bangladesh on Sunday:
tropical cyclones
Cyclones are low pressure systems that form over warm tropical waters with gale force winds near the center. Winds can increase for hundreds of kilometers (miles) from the eye of the storm.
By absorbing huge amounts of water, they often produce torrential rains and floods that result in great loss of life and property.
When they reach sustained winds of at least 119 kilometers per hour (74 mph), they are also known as hurricanes or typhoons, depending on where in the world they originate.
According to NASA, tropical cyclones (hurricanes) are the most powerful weather phenomena on Earth.
storm surge
When cyclones hit, they can bring devastating storm surges – tsunami-like floods. They can be the deadliest part of a cyclone and are only partially affected by wind speed.
The term “storm surge” refers to a rising sea spurted by a storm, which creates a wall of water several meters higher than the normal tide level.
Large waves move faster than cyclones and are sometimes seen up to 1,000 kilometers ahead of a large storm.
The surge can spread dozens of kilometers inland, overwhelming homes and making roads impassable.
Storm surge is shaped by many different factors, including storm intensity, forward speed, size of the storm, and angle of approach to the coast.
The inherent features of the land on the coast, including bays and estuaries, are also at play.
In previous storms, people failed to escape because they did not understand the deadly danger of the surge.
This was the case for Super Typhoon Haiyan of 2013, which killed 7,350 people or went missing in the central Philippines, mainly due to surge.
According to the India Meteorological Department, a storm surge of up to three meters (10 feet) is expected over low-lying areas of Myanmar’s Rakhine state and eastern Bangladesh.
low-lying areas
Bangladesh, a lower delta nation, is regularly hit by bad storms between April and December that cause deaths and massive property damage.
According to experts, Bangladesh is vulnerable to cyclones due to its location at the triangular-shaped head of the Bay of Bengal, the geography of its coastal region and its high population density.
Hundreds of people living around the Bay of Bengal have died in cyclones in recent decades.
The death toll has decreased over the years due to rapid evacuation and the construction of thousands of coastal shelters.
Bay of Bengal
According to the World Meteorological Organisation, the tropical cyclone season in the Bay of Bengal and the neighboring Arabian Sea has two peaks around May and November.
Cyclones can form in the western Pacific Ocean and travel in a northwesterly direction before reaching the Bay of Bengal.
The Bay of Bengal has favorable conditions for the development of cyclones, including high sea surface temperatures.
Some of the deadliest storms in history have formed in the Bay of Bengal, including a storm in 1970 that killed half a million people in what is now Bangladesh.
In 1991, a tidal wave caused by a cyclone in Bangladesh killed about 138,000 people.
In 1999, 10,000 people were killed by a cyclone in Odisha.
In 2007, Cyclone Sidra killed at least 4,000 people in southern Bangladesh.
Then in 2008 Cyclone Nargis, which devastated Myanmar’s Irrawaddy Delta, killed at least 138,000 people.
Climate change
Studies suggest that a warmer climate may bring more destructive cyclones because there will be additional heat in the oceans and atmosphere, although such systems may also become less frequent.
Rising sea levels can boost storm surges from cyclones, making them more deadly and destructive.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)