From UPSC perspective, the following things are important :
Prelims level : Hurricane (Tropical Cycolnes)
Mains level : Impact of frequent cyclonic landfalls
Hurricane Ida has made landfall in Louisiana, US as an extremely dangerous Category 4 storm.
What is a Hurricane?
- A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and the northeastern Pacific Ocean.
- And a typhoon occurs in the northwestern Pacific Ocean; in the south Pacific or the Indian Ocean, comparable storms are referred to simply as “tropical cyclones” or “severe cyclonic storms”.
What are Tropical Cyclones?
A Tropical cyclone is an intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain.
- Cyclones are formed over slightly warm ocean waters. The temperature of the top layer of the sea, up to a depth of about 60 meters, need to be at least 28°C to support the formation of a cyclone.
- This explains why the April-May and October-December periods are conducive for cyclones.
- Then, the low level of air above the waters needs to have an ‘anticlockwise’ rotation (in the northern hemisphere; clockwise in the southern hemisphere).
- During these periods, there is an ITCZ in the Bay of Bengal whose southern boundary experiences winds from west to east, while the northern boundary has winds flowing east to west.
- Once formed, cyclones in this area usually move northwest. As it travels over the sea, the cyclone gathers more moist air from the warm sea which adds to its heft.
Try this question from CSP 2020:
Q.Consider the following statements:
- Jet Streams occur in the Northern Hemisphere only.
- Only some cyclones develop an eye.
- The temperature inside the eye of a cyclone is nearly 10 degree Celsius lesser than that of the surroundings.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1 and 3 only
Post your answers here.
- Strong Winds: Cyclones are known to cause severe damage to infrastructure through high-speed winds.
- Torrential rains and inland flooding: Torrential rainfall (more than 30 cm/hour) associated with cyclones is another major cause of damages. Unabated rain gives rise to unprecedented floods.
- Storm Surge: A Storm surge can be defined as an abnormal rise of sea level near the coast caused by a severe tropical cyclone.
Some (unexpected) benefits
Although Tropical cyclones are known for the destruction they cause, when they strike they also bestow certain benefits to the climatic conditions of that area such as
- Relieve drought conditions
- Carry heat and energy away from the tropics and transport it towards temperate latitudes
- Maintain a relatively stable and warm temperature worldwide