Cyclone Fengal

Syllabus: GS1/Geophysical Phenomena

Context

• Cyclone Fengal, a tropical cyclone, made landfall over Puducherry.

About

• Landfall is the event of a tropical cyclone coming onto land after being over water.
  • As per the India Meteorological Department (IMD), a tropical cyclone is said to have made landfall when the centre of the storm – or its eye – moves over the coast.
  • Landfalls can last for a few hours, with their exact duration depending on the speed of the winds and the size of the storm system.
• A landfall is different from the direct hit of a tropical cyclone.
  • A ‘direct hit’ refers to a situation where the core of high winds (or eyewall) comes ashore but the centre of the storm may remain offshore.

What are Cyclones?

• The word Cyclone is derived from the Greek word Cyclos meaning the coils of a snake.
  • It was coined by Henry Peddington because the tropical storms in the Bay of Bengal and the Arabian Sea appear like coiled serpents of the sea.
• Cyclones are powerful, rotating storms that form over warm ocean waters, characterized by low pressure at the center and high winds.

• Worldwide terminology: Cyclones are given many names in different regions of the world:
  • They are known as typhoons in the China Sea and Pacific Ocean; hurricanes in the West Indian islands in the Caribbean Sea and Atlantic Ocean; tornados in the Guinea lands of West Africa and southern USA.; willy-willies in north-western Australia and tropical cyclones in the Indian Ocean. 

How a Cyclone is formed?

• Conditions: Cyclones typically form over warm ocean waters, the warmth provides the necessary heat and moisture to fuel the cyclone.
  • Warm water causes the ocean to evaporate, creating warm, moist air. This moist air rises from the ocean surface, leading to a decrease in air pressure at the surface.
• Formation of a Low-Pressure System: When the air rises up and away from the ocean surface, it creates an area of lower air pressure below. 
  • It causes the air from surrounding areas with higher pressure to move towards the low-pressure area which further leads to warming up of the air and causes it to rise above.
• Cyclonic Circulation: The rotation of the Earth (Coriolis effect) causes the rising air to start spinning around the low-pressure center. This spinning motion leads to the development of cyclonic circulation.

• As the wind system rotates with increasing speed, an eye gets formed in the middle.
  • The centre of a cyclone is very calm and clear with very low air pressure. The difference of temperature between the warm, rising and the cooler environment causes the air to rise and become buoyant.
• Dissipation: A cyclone will eventually weaken and dissipate when it moves over cooler waters, encounters dry air, or interacts with land, which disrupts the system’s supply of warm, moist air.

Nomenclature

• The names are maintained and updated by an international committee of the World Meteorological Organization.
• Cyclones in the North Indian Ocean region are named by the regional specialized meteorological centers (RSMCs) in India, Bangladesh, Myanmar, Oman, Pakistan, and Sri Lanka.
  • Each country contributes names to a list used on a rotating basis.
• The primary reason for naming cyclones is to make communication easier and more efficient. 

Source: TH