Cyclone Yaas to strike India after Tauktae

Another cyclone is set to reach the eastern coast of India by 26th May. A low-pressure area is expected to develop over the north Andaman Sea and the adjacent east-central Bay of Bengal about 22nd May, according to the India Meteorological Department (IMD). By 24th May, it is expected to become a cyclonic storm. The storm is expected to pass northwestward and enter the north Bay of Bengal near the Odisha-West Bengal coast about May 26, according to the weather service. Cyclone Yaas is the name provided by the department.

This will be India's second cyclone in less than two weeks. Cyclone Tauktae, which originated in the Arabian Sea, made landfall in Gujarat just last week.

How did these cyclones form?

In the tropical zone, cyclones emerge over the oceanic water. The sun shines brightest in this region, causing the land and water surface to warm. Cold moist air over the ocean rises as the surface warms, and cool air floods in to fill the vacuum, becoming warm and rising as well — the cycle continues.

What causes the spin, though? Wind often blows from areas of high pressure to areas of low pressure. In the cold, high-pressure areas form, while in the humid, low-pressure areas form. Since the amount of sunlight in the polar regions is less than in the tropical regions, they are high-pressure zones. As a result, the wind blows from polar to tropical regions.

Then there's the west-to-east movement of the Earth. The wind is deflected by the Earth's rotation on its axis (in the tropical area since the Earth's speed of spinning is faster than the polar sides due to its spherical shape — blowing from both polar regions). The wind from the Arctic is deflected to the right, while the wind from Antarctica is deflected to the west.

As a result, the wind is already flowing in a particular direction. When it enters a warmer place, however, cold air is drawn to the centre to fill the void. As the cyclone moves closer to the centre, cold air is deflected, causing wind movement to circulate — this process continues until the cyclone reaches land.

When a cyclone enters the land, it dissolves because the warm water that arises to make room for cool water is no longer safe. In addition to this, as moist air rises, clouds form, resulting in rains that accompany strong winds during cyclones.