UP PCS Mains-2024

Approach Give a brief description about cyclone and its types. Highlight the differences between tropical and extra tropical cyclones. Illustrate through diagrams and give a concluding statement.

Introduction

Cyclones are rapid inward air circulation around a low-pressure area. The air circulates in an anticlockwise direction in the Northern hemisphere and clockwise in the Southern hemisphere. They are formed when warm, moist air over the ocean rises upward from near the surface. They are usually accompanied by violent storms and bad weather. They are classified into tropical and extratropical cyclones based on their origin and characteristics.

Body

Major differences between Tropical and Extratropical cyclones:

Basis	Tropical Cyclone	Extra-tropical Cyclone
Characteristics	A low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain.	A large-scale low-pressure weather system that occurs in the middle latitudes of the Earth
Formation	It gets intensified over warm tropical oceans and requires temperature higher than 27° C, presence of the Coriolis force, small variations in the vertical wind speed, a pre-existing weak low- pressure area or low-level-cyclonic circulation and upper divergent above the sea level system.	It gets intensified in any part of extratropical regions of the Earth (usually between 30° and 60° latitude from the equator), either through cyclogenesis or extratropical transition.
Energy Source	Warm ocean temperatures and latent heat release	Temperature differences (cold and warm air masses)
Movement	It moves from east to west.	It moves from west to east.
Nature of Cyclone	Violent storms	Static, not violent
Type	Warm Core	Cold Core
Region	Tropics of Capricorn and Cancer	Temperate zones and high latitude regions
Wind Velocity and destruction	Much greater (100 – 250 kmph) (200 – 1200 kmph in upper troposphere) Greater destruction due to winds, storm surges and torrential rains.	Comparatively low. Typical range: 30 – 150 kmph. Less destruction due to winds but more destruction due to flooding.
Season	It is seasonal. Occurs in late summers (Aug – Oct).	It is Irregular as few occur in summers and more in winters.
Rainfall	Rainfall is heavy but does not last beyond a few hours. If the cyclone stays at place, the rainfall may continue for many days.	Rainfall is slow and continues for many days, sometimes even weeks.
Isobars	Complete circles and the pressure gradient are steep	Isobars are usually ‘V’ shaped, and the pressure gradient is low.
Lifetime	Doesn’t last for more than a week	Usually lasts for 2-3 weeks.
Calm region	The center of a tropical cyclone is known as the eye. The wind is calm at the center with no rainfall.	In a temperate cyclone, there is not a single place where winds and rains are inactive.
Impact on India	Both coasts are affected. But the east coast is the hot spot.	Bring rains to North – West India. The associated instability is called ‘Western Disturbances’.

Conclusion

Both tropical and temperate cyclones cause devastating impacts leading to loss of life and property. It causes local as well as global impacts affecting the weather system of the world. Therefore, it is crucial to study their causes, work on its mitigation and management in view of the growing blue economy of the world.