Mains Daily Question
Nov. 11, 2020
- Compare the origin and weather conditions associated with the tropical and temperate cyclones. (10 marks)
- Introduce with cyclones
- Compare the origin of the cyclones - in terms of causes, location, mechanism etc.
- Compare the weather conditions associated with each of them.
- Conclude appropriately
A cyclone is a low-pressure area in the atmosphere in which winds spiral inward. On the basis of their area of origin, they are classified as: Temperate cyclones and Topical cyclones.
Cyclones developed in tropics region (majority confined to 100– 300 N and S of equator) are called tropical cyclones.
- The tropical cyclones have a thermal origin, and they develop over tropical seas during certain seasons. Pre-existing low pressure, large sea surface with temperature higher than 27° C, and presence of the Coriolis force are a must for tropical cyclone formation.
- At these locations, the local convectional currents acquire a whirling motion because of the Coriolis force generated by the earth’s rotation. After developing, these cyclones advance till they find a weak spot in the trade wind belt.
- Tropical cyclones always origin in large water bodies.
Temperate cyclones (Mid-Latitude cyclones), also known as Extratropical cyclones, are active over mid-latitudinal region between 35° latitude and 65° latitude in both hemispheres.
- They have a dynamic origin and cyclone formation is due to frontogenesis (interaction of cold and warm fronts). When the warm-humid air masses from the tropics meet the dry-cold air masses from the poles and thus a polar front is formed as a surface of discontinuity. The cold air pushes the warm air upwards from underneath. Thus, a void is created because of lessening of pressure. The surrounding air rushed in to occupy this void and coupled with the earth’s rotation, a temperate cyclone is formed.
- Temperate cyclones can origin on both landmass or water.
- Tropical Cyclones: The tropical cyclones are associated with heavy rain fall and high velocity of winds for short duration at small area. So, here greater destruction is due to winds, storm surges and torrential rains.
- Temperate Cyclones: On the other hand, temperate cyclone associated weather conditions are mild and overcast sky in initial stage and followed by moderate to heavy rain for long period of time on large area. So, here less destruction is due to winds but more destruction is due to flooding.
Because of India's tropical location, it mostly gets effected by Tropical cyclones along a large part of its coast. Temperate cyclones are also of significance as they play a major role in bringing rain to the North-west India popularly known as Western Disturbances.