A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level wind circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain.
The term tropical refers to the geographical origin of these systems, which form almost exclusively over tropical seas. In addition to strong winds and rain, tropical cyclones are capable of generating high waves, damaging storm surge, and tornadoes.
Tropical cyclones derive their energy from the evaporation of water from the ocean surface, which ultimately recirculates as water vapor into the atmosphere.
Horizontally, it extends up to 500-1,000 km and vertically from surface to 12-14 km. A tropical cyclone or hurricane is like a heat engine that is energised by the release of latent heat on account of the condensation of moisture that the wind gathers after moving over the oceans and seas.
Some initial conditions for the emergence of a tropical cyclone are:
- Large and continuous supply of warm and moist air that can release enormous latent heat.
- Strong Coriolis force that can prevent filling of low pressure at the centre (absence of Coriolis force near the equator prohibits the formation of tropical cyclone between 0° -5° latitude).
- Unstable condition through the troposphere that creates local disturbances around which a cyclone develops.
- Finally, absence of strong vertical wind wedge, which disturbs the vertical transport of latent heat.
