About Tropical Cyclone:
- Formation:
- These cyclones originate over warm ocean waters near the equator. Warm, moist air rises from the ocean surface, creating a low-pressure area.
- Surrounding higher-pressure air moves towards this low-pressure zone, causing the air to warm up and rise further. As the rising air cools, it forms clouds.
- This system of spinning clouds and wind intensifies with the ocean’s heat. As wind speeds increase, an eye forms at the centre.
Characteristics of a Tropical Cyclone:
- Calm centre: The cyclone’s centre is typically calm and clear, with very low air pressure.
- Speed: The average wind speed is around 120 km/h.
- Closed isobars: These cyclones have closed isobars, leading to higher wind velocities.
- Origin: They form exclusively over oceans and seas.
- Movement: Tropical cyclones move from east to west, are influenced by trade winds, and are seasonal.
Classification of Cyclones:
- Cyclones are categorised by the Indian Meteorological Department (IMD) based on wind speeds:
- Depression: Wind speeds between 31–49 km/h
- Deep depression: Wind speeds between 50-61 km/h
- Cyclonic storm: Wind speeds between 62–88 km/h
- Severe cyclonic storm: Wind speeds between 89-117 km/h
- Very severe cyclonic storm: Wind speeds between 118-166 km/h
- Extremely severe cyclonic storm: Wind speeds between 166-221 km/h
- Super cyclonic storm: Wind speeds above 222 km/h
Naming of Tropical Cyclones:
- Tropical cyclones are named by one of five regional bodies:
- ESCAP/WMO Typhoon Committee
- WMO/ESCAP Panel on Tropical Cyclones
- RA I Tropical Cyclone Committee
- RA IV Hurricane Committee
- RA V Tropical Cyclone Committee
- In the Indian Ocean, the WMO/ESCAP Panel on Tropical Cyclones is responsible for naming cyclones.
