Cyclone Nivar has made landfall along the Tamil Nadu-Puducherry coast as the state hunkered down to face the “very severe” cyclone—its fifth major one in the last eight years.
Cyclone Nivar was the fourth cyclone to take shape in the North Indian Ocean region in 2020.
The first three cyclones were Cyclone Gati (made landfall in Somalia on November 22), Cyclone Amphan, (eastern India witnessed it in May), and Cyclone Nisarga (in Maharashtra).
Nivar was the second cyclone to hit Tamil Nadu in two years after Cyclone Gaja in 2018.
According to the meteorological department, a deep depression over the Bay of Bengal turned into a severe cyclonic storm and hit the coasts of Tamil Nadu and Puducherry on November 25.
The storm has been named Cyclone Nivar, based on the guidelines of the World Meteorological Organisation (WMO). According to WMO guidelines, countries in every region are supposed to give names for cyclones.
North Indian Ocean Region covers tropical cyclones formed over Bay of Bengal and Arabian Sea. The 13 members, which come under the region, are Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka and Thailand. In 2018, five more countries were added. These are Iran, Qatar, Saudi Arabia, the UAE and Yemen.
A total of 169 cyclones were named by these countries for this year, with 13 names from each country. Every member’s name is listed in alphabetical order and the cyclone names are used sequentially column-wise.
Cyclones are named to make their identification easier. It is also believed that names like these make it easier for the media to report and generates interest from the people, resulting in easier dissemination of information and increased preparedness.
The name Nisarga was given by Bangladesh, Gati was taken from India’s suggested names. Nivara has been selected from the list of names given by Iran.
Tropical cyclones are low pressure systems that form over warm tropical waters. They typically form when the sea-surface temperature is above 26.5°C.
Tropical cyclones can continue for many days, even weeks, and may follow quite erratic paths. A cyclone will dissipate once it moves over land or over cooler oceans.
The tropical cyclone is formed when a transfer of water vapour and heat from the warm ocean to the overlying air occurred primarily by evaporation from the surface of the sea.
Tropical cyclones winds swirl around a central region of low atmospheric pressure. The wind is caused due to the low-pressure core and by the rotation of Earth, which further deflects the path of the wind via a phenomenon known as the Coriolis force.
In the Northern Hemisphere, tropical cyclone rotates in a counter-clockwise or cyclonic direction and in the Southern Hemisphere, it rotates in a clockwise or anticyclonic direction.