ENVIRONMENT & ECOLOGY
News: Cyclone Titli to make landfall in Odisha today.
Source: The Hindu
Severe Cyclonic Storm Titli was a strong tropical cyclone that devastated parts of Andra Pradesh and Odisha in India. Titli was the most intense tropical cyclone in the Bay of Bengal in 2018. Due to high atmospheric moisture and warmer oceanic surface temperatures between Gopalpur and Northern Andra Pradesh in mainland India, Titli intensified into a Cyclonic Storm.
Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large scale destruction due to violent winds (squalls), very heavy rainfall (torrential rainfall) and storm surge.
They are irregular wind movements involving closed circulation of air around a low pressure center. This closed air circulation (whirling motion) is a result of rapid upward movement of hot air which is subjected to Coriolis force. The low pressure at the center is responsible for the wind speeds.
Conditions Favorable for Tropical Cyclone Formation
• Large sea surface with temperature higher than 27° C,
• Presence of the Coriolis force enough to create a cyclonic vortex,
• Small variations in the vertical wind speed,
• A pre-existing weak low-pressure area or low-level-cyclonic circulation,
• Upper divergence above the sea level system
Why tropical cyclones don’t form in the eastern tropical oceans?
The depth of warm water (26-27°C) should extend for 60-70 m from surface of the ocean/sea, so that deep convection currents within the water do not churn and mix the cooler water below with the warmer water near the surface.
The above condition occurs only in western tropical oceans because of warm ocean currents (easterly trade winds pushes ocean waters towards west) that flow from east towards west forming a thick layer of water with temperatures greater than 27°C. This supplies enough moisture to the storm.
The cold currents lower the surface temperatures of the eastern parts of the tropical oceans making them unfit for the breeding of cyclonic storms.