Cyclone Yaas develops over Bay of Bengal

Context: A low-pressure area formed over the North Andaman Sea and adjoining east-central Bay of Bengal around May 22, 2021, and has further intensified into a severe cyclonic storm, named ‘Cyclone Yaas’.
About

• Cyclone Yaas has been classified as a ‘Very Severe Cyclonic Storm (VSCS)’.
• The word has originated from the Persian language and mean ‘Jasmin’ in English.
• The cyclone has been named Yaas by Oman.
• West Bengal, Orisha, Assam and Meghalaya are those Indian states that are expected to be affected.

Note: 13 countries of the World Meteorological Organization/United Nations Economic and Social Commission for Asia and the Pacific (WMO/ESCAP) Panel on Tropical Cyclones (PTC) name the cyclones
How are cyclones formed?

• Cyclones are formed over the oceanic water in the tropical region.
• In this region, the sunlight is highest which results in warming of land and water surface. Due to warming of the surface, the warm moist air over the ocean rises upwards following which cool air rushes in to fill the void, they too get warm and rise — the cycle continues.

But what creates the spin?

• Wind always blows from high pressure to low pressure areas. High pressure areas are created in the cold region while low is created in the warm regions. Polar regions are high pressure areas as the amount of sunlight here is less than the tropical region. So, wind blows from polar regions to tropical regions.
• Then comes the Earth’s movement, which is west to east. The Earth’s rotation on its axis causes deflection of the wind (in the tropical region as the speed of spinning of Earth is higher compared to polar sides due to its spherical shape — blowing from both the polar regions. Wind coming from the Arctic is deflected to the right while Antarctic wind deflects to the left side.
• So, wind is already blowing in a direction. But when it reaches the warmer place, cool air starts getting attracted to the centre to fill the gap. So while moving to the centre, cool air keeps getting deflected resulting in circulation of wind movement — this process continues until the cyclone hits the land.

What happens when a cyclone hits the land?

• Cyclone dissipates when it hits the land as the warm water that rises and creates space for cool water is no longer available on land. Also, the moist air that rises up forms clouds leading to rains that accompany gusting winds during cyclones.