By Pradeep Kumar
Timing and strength are two factors that make Cyclone Fani, different from most other tropical cyclones in May 2019. The trajectory made Fani special as it started developing near the Equator around April 25, traversed for nearly 10 days over the sea upwards to gather a lot of moisture and momentum, resulting in strong winds to be classified as an extremely severe cyclone.
Generally, tropical cyclones over the Bay of Bengal (BoB) have four-seven days’ lifespan. It has been observed that cyclones/hurricanes/tornados travelling over the sea for longer time generally are more powerful than the ones that hit the landmass within a few days, according to Mukesh Rawat.
Cyclone Fani classified as an extremely severe cyclone (ESC) is the 10th such cyclone to hit India in May in past 52 years. IMD Data show that another ESC hit India in May 2004. Other such cyclones in May were: 1968, 1976, 1979, 1982, 1997, 1999 and 2001.
Generally, extremely severe cyclones hit India’s east coast in post-monsoon season (October-December). IMD data on cyclones that hit India between 1965 and 2017 show that the country has weathered 39 ESCs in last 52 years. Of these, nearly 60% (23) were between October and December.
The cyclones are classified as severe [maximum surface wind (MSW of 48-63 knots), very severe (MSW of 64-89 knots), extremely severe (MSW of 90-119 knots) and super cyclonic storm (MSW of 120 knots or more). One knot is equal to 1.8 kmph.
The IMD had first predicted that Cyclone Fani would make a landfall in Tamil Nadu but the forecast was updated as it altered its course. Had Cyclone Fani made its landfall in Tamil Nadu, it would not have been ESC because of shorter distance over the sea.
Most cyclones exclusively that generating in the BoB became relatively weaker by the time they reach the Indian landmass. The World Meteorological Organisation (WMO), a United Nations body that monitors weather conditions, had said the extremely severe Cyclone Fani will make a landfall in Odisha with wind speeds of more than 170 km/h. However, it will move north-northeastwards and strike West Bengal as a severe cyclone and is expected to hit Bangladesh on May 4 as a cyclonic storm as it will travel considerable distance over the land.
Ministry of Earth Sciences secretary Madhavan Rajeevan, in a tweet said, “In the past (1891-2017) only 14 ESCs were formed in April over the BoB and only one storm crossed the Indian mainland. Cyclone Fani is the second storm forming in April and crossing the mainland. The last time it happened was Cyclone Nargis that devastated Myanmar in 2008.”
Sources of cyclones: The Indian subcontinent experiences cyclones from two basins: the BoB basin and the Arabian Sea basin. More cyclones are generated in the BoB, more severe than the one generated over the Arabian Sea.
Tropical cyclones are more prone to the BoB as its surface temperature is more than that of the Arabian Sea. Tropical cyclones generally need a temperature of around 28°C and the BoB is more conducive to this than the Arabian Sea.
Data on cyclones that hit India over the past 126 years also back this theory. On analysing IMD data it is found that between 1891 and 2017, India weathered 305 cyclones that were classified as severe and above. Of these, 75% (229) were generated in the BoB basin.
Another peculiarity with the BoB is that it is known for its potential in generating dangerous high storm tides. When these tides and cyclonic storms coincide, it becomes a major killer.
Gloomy past: The Indian subcontinent is considered to be one of the worst-affected regions by tropical cyclones for witnessing some of the deadliest cyclones in world history.
According to the Nation Cyclone Risk Mitigation Project (NCRMP), the Indian subcontinent is exposed to “nearly 10%” of the world’s tropical cyclones. NCRMP’s data analysis shows that between 1980 and 2000, on an average annually 370 million (37,00,000) people were exposed to cyclones in India.
“Out of 10 recorded cases of very heavy loss of life (ranging from about 40,000 to well over 2,00,000) in the world due to tropical cyclones, nine cases were in the BoB and the Arabian Sea,” as per the IMD. Five of these were in Bangladesh, three in India and one in Myanmar.
World’s highest recorded storm tide measuring 45 feet occurred in 1876 during the Bakherganj cyclone near Meghna Estuary, Bangladesh.
A 2014 report of the WMO), states that cyclonic storms have been the main cause of deaths due to natural disasters in Asia between 1970 and 2012. A majority of these cyclone-related deaths have occurred in India and Bangladesh.
The report–Atlas of Mortality and Economic Losses from Weather, Climate and Water Extremes–states that between 1970 and 2012, Asia suffered 2,681 natural disasters, of which 35% (938) were storms.
When it comes to deaths, cyclonic storms were responsible for 76% of all deaths caused by natural disasters in Asia in this period. (The report estimates 9.15 lakh deaths were caused due to natural disasters in Asia and 6.95 of them were related to tropical cyclones.)
The top three deadliest disasters in this period were all tropical cyclones. Two of them hit Bangladesh (in 1970 and 1991) and one hit Myanmar (Cyclone Nargis in 2008). The total deaths caused by these three cyclones was 5, 77, 232.
Of the 10 most severe natural disasters (in terms of deaths) that struck Asia between 1970 and 2012, eight were tropical storms that hit India, Bangladesh and Myanmar.
In terms of economic loss, Asia suffered a loss of $789.8 billion in these 42 years and 30% of it was due to cyclonic storms.
Besides this, analysis of the WMO data show that between 1970 and 2012, 7,77,861 people were killed due to storms (cyclones/hurricanes/tornadoes). However, 89 per cent of the deaths (6.95 lakh) were caused in Asia, and primarily in Bangladesh, Myanmar and India.
Why do hurricanes have eyes? A cyclone’s eye is a place of safety and a sign of danger. Inside the eye, winds are calm and no rain falls. Blue skies are usually visible overhead. But ending up inside a storm’s eye is bad as the eye is ringed by the eye wall, where the storm’s most powerful winds swirl. And when an eye forms, it’s a sign that a cyclone has grown more organized, and more powerful. It’s a key step on the road to becoming a fully-fledged hurricane.
So, meteorologists watch cyclonic eyes carefully. Those strange, still spots convey invaluable information about what destruction a storm will wreak. And yet, despite researchers’ intense focus on the phenomena, cyclone eyes are barely understood. A paper published in 2006 found hundreds of explanations for cyclone eye formation, many of them explicitly contradicting one another, Rafi Latzter reported on 2.01.18
Super Typhoon Maysak eye image taken by European Space Agency astronaut Samantha Cristoforetti on board the International Space Station 07.08.17Credit: ESA/NASA/Samantha Cristoforetti
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