Cyclone Biparjoy: What is a Cyclone and What are Its Types?

What’s in today’s article?

• Why in News?  
• About Tropical Cyclone
• Characteristics of a Tropical Cyclone
• How are Cyclones Classified?
• How are Tropical Cyclones Named?
• About WMO/ESCAP Panel
• What is an Extratropical Cyclone?
• How an Extratropical Cyclone is Formed?

 

Why in News?  

• Developed in the Arabian Sea, cyclone Biparjoy is heading towards the northern Gujarat coast, with landfall expected on June 15.

 

About Tropical Cyclone

 

Image Caption: Tropical Cyclone

• Tropical Cyclone is a weather phenomenon.
• A tropical cyclone is formed only over warm ocean waters near the equator.
• Warm, moist air rises up and away from the ocean surface, creating an area of low pressure.
• It causes the air from surrounding areas with higher pressure to move towards the low-pressure area.
• This leads to warming up of air and causes it to rise above.
• As the air rises & cools, the water in the air forms clouds.
• This complete system of clouds and wind spins & grows, along with the ocean’s heat.
• As the wind rotation speed increases, an eye gets formed in the middle.

 

Characteristics of a Tropical Cyclone

• The centre of a cyclone is very calm and clear with very low air pressure.
• The average speed is 120 kmph.
• They have closed isobars which leads to greater velocity.
  • Isobars are imaginary lines on a weather map that connect locations with equal atmospheric pressure.
• They develop over oceans and sea only.
• They move from east to west under the influence of trade winds.
• They are seasonal in nature.

 

How are Cyclones Classified?

• Cyclones are classified on the basis of wind speed by the Indian Meteorological Department (IMD):
  • Depression: Wind speeds of between 31–49 km/h
  • Deep Depression: Between 50-61 km/h
  • Cyclonic Storm: Between 62–88 km/h
  • Severe Cyclonic Storm: Between 89-117 Km/h
  • Very Severe Cyclonic Storm: Between 118-166 Km/h
  • Extremely Severe Cyclonic Storm: Between 166-221 Km/h
  • Super Cyclonic Storm: Above 222 Km/h

 

How are Tropical Cyclones Named?

• Tropical cyclones have different names depending on their location and strength.
• For instance, they are known as hurricanes in the Caribbean Sea, the Gulf of Mexico, the North Atlantic Ocean and the eastern and central North Pacific Ocean.
• In the western North Pacific, they are called typhoons.
• In the Indian Ocean, they are known as cyclones.
• There are five tropical cyclone regional bodies in the world:
  • ESCAP/WMO Typhoon Committee,
  • WMO/ESCAP Panel on Tropical Cyclones,
  • RA I Tropical Cyclone Committee,
  • RA IV Hurricane Committee,
  • RA V Tropical Cyclone Committee.
• WMO/ESCAP Panel on Tropical Cyclones is responsible for naming of cyclones in the Indian Ocean.

 

About WMO/ESCAP Panel

• It is an inter-governmental regional body jointly established by the World Meteorological Organization (WMO) and the United Nations Economic and Social Commission for Asia-Pacific (ESCAP) in 1972.
• Objective:
  • To promote measures to improve tropical cyclone warning systems in the Bay of Bengal and the Arabian Sea region.
• It comprises of thirteen countries in the region – Bangladesh, India, Iran, Maldives, Myanmar, Oman, Pakistan, Qatar, Saudi Arabia, Sri Lanka, Thailand, United Arab Emirates, Yemen.
• They contribute to a set of names which are assigned sequentially whenever a cyclonic storm develops.

 

What is an Extratropical Cyclone?

• Extratropical cyclones are low-pressure areas which are generally formed outside the tropics with a latitude range between 30 degrees and 60 degrees.
• They are also known as temperate cyclones.
• These low-pressure systems are associated with cold fronts, warm fronts, and occluded fronts.

 

How an Extratropical Cyclone is Formed?

 

Image Caption: Formation of Extratropical cyclone

• In the Northern hemisphere, cold air blows from the north of the front and warm air blows from the south.
• When the pressure descents along the front, the cold air move towards the south, and the warm air moves northwards setting in motion an anticlockwise cyclonic circulation.
• The cyclonic circulation results in a well-built extratropical cyclone, with a cold front and a warm front.
• There are pockets of warm air compressed between the forward and the rear cold air.
• The warm air climbs over the cold air and a series of clouds appear over the sky ahead of the warm front and cause rainfall.
• The cold front approaches the warm air from behind and pushes the warm air up.
• As an outcome, cumulus clouds develop along the cold front.
• The cold front moves faster than the warm front eventually surpassing the warm front.
• The warm air is entirely lifted and the front is occluded and the cyclone dissipates.
• They can originate over the land and sea and cover a larger area.

 

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Q1) What is the meaning of Tropics?

The tropics are regions of Earth that lie roughly in the middle of the globe. The tropics between the latitude lines of the Tropic of Cancer and the Tropic of Capricorn.

 

Q2) What is an Anticyclone?

Anticyclone is any large wind system that rotates about a center of high atmospheric pressure clockwise in the Northern Hemisphere and counterclockwise in the Southern. Its flow is the reverse of that of a cyclone

 

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Source: Cyclone Biparjoy: What is a cyclone and what are its types