- Tropical cyclone, also called typhoon or hurricane, an intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain.
- Drawing energy from the sea surface and maintaining its strength as long as it remains over warm water, a tropical cyclone generates winds that exceed 119 km (74 miles) per hour. In extreme cases winds may exceed 240 km (150 miles) per hour, and gusts may surpass 320 km (200 miles) per hour.
- Accompanying these strong winds are torrential rains and a devastating phenomenon known as the storm surge, an elevation of the sea surface that can reach 6 metres (20 feet) above normal levels.
- Such a combination of high winds and water makes cyclones a serious hazard for coastal areas in tropical and subtropical areas of the world. Every year during the late summer months (July–September in the Northern Hemisphere and January–March in the Southern Hemisphere), cyclones strike regions as far apart as the Gulf Coast of North America, northwestern Australia, and eastern India and Bangladesh.
Different names of tropical cyclones
- Tropical cyclones are known by various names in different parts of the world. In the North Atlantic Ocean and the eastern North Pacific they are called hurricanes, and in the western North Pacific around the Philippines, Japan, and China the storms are referred to as typhoons.
- In the western South Pacific and Indian Ocean they are variously referred to as severe tropical cyclones, tropical cyclones, or simply cyclones.
- All these different names refer to the same type of storm.
Conditions for formation of tropical cyclones
- The temperature of the surface layer of ocean water must be 26.5 °C (80 °F) or warmer, and this warm layer must be at least 50 metres (150 feet) deep.
- A preexisting atmospheric circulation must be located near the surface warm layer.
- The atmosphere must cool quickly enough with height to support the formation of deep convective clouds.
- The middle atmosphere must be relatively humid at a height of about 5,000 metres (16,000 feet) above the surface.
- The developing system must be at least 500 km (300 miles) away from the Equator.
- The wind speed must change slowly with height through the troposphere—no more than 10 metres (33 feet) per second between the surface and an altitude of about 10,000 metres (33,000 feet).
An extremely powerful cyclone; (Meteorology) a tropical cyclone with sustained wind speeds in excess of 130 knots (240 km per hour) in the region of the Arabian Sea, Indian Ocean, and Bay of Bengal.
Cyclone Amphan-Super Cyclone
- Cyclone Amphan has now intensified into a super cyclonic storm on Monday and is likely to move across the northeast Bay of Bengal, and cross the West Bengal and Bangladesh coasts between Digha and the Hatia Island on May 20, according to the Indian Meteorological Department (IMD).
- ‘Amphan’ (pronounced UM-PN) that had turned into an extremely severe cyclonic storm gathered more strength over the Bay of Bengal while moving slowly towards the coast. It has now intensified further into a super cyclonic storm likely to make landfall on Wednesday, the IMD has indicated.
- The IMD has warned that the cyclone could ravage east Medinipur, south and north 24 Parganas, Howrah, Hooghly and Kolkata districts in West Bengal.
- Twenty-one years ago, in 1999, another super cyclonic storm had ravaged large parts of Odisha and Gangetic West Bengal. It had taken Odisha, a number of months to repair the extensive damage that the Super Cyclone had caused back then.
- The state is expected to face extensive damage in the storm that is likely to uproot communication and power poles. It said the Cyclone Amphan could also disrupt rail and road links in many places in Bengal and Odisha and inflict extensive damage to standing crops, plantations and orchards.
1. Cyclone Amphan is likely to move north-northeastwards and rapidly across the northwest Bay of Bengal, and cross the West Bengal and Bangladesh coasts between Digha and the Hatia Island as a very severe super cyclonic storm.
2. This has raised the possibility of heavy rains and high-velocity winds in coastal Odisha and Bengal and the state governments have initiated the process of evacuating people from vulnerable areas.
3. Cyclone Amphan is likely to have a wind speed of up to 185 km per hour on Wednesday, the Union Home Ministry has said in its latest update.
4. Heavy rainfall warnings have been issued by the IMD for Gajapati, Puri, Ganjam, Jagatsinghpur, and Kendrapara. On Tuesday, the rainfall activity is likely to increase in Balasore, Bhadrak, Jajapur, Mayurbhanj, Khurja and Cuttack in Odisha.
5. Fishermen have been advised not to venture into the sea till May 21, Special Relief Commissioner (SRC) P K Jena has said. The IMD has issued a warning to suspend all fishing activity in Bengal and Odisha till May 20.
6. The National Disaster Response Force (NDRF) has enhanced its strength to a total of 37 teams, with the addition of 20 more, to combat the dual challenge of Cyclone Amphan and the coronavirus pandemic, the chief of the federal contingency force said on Monday.
7. The Odisha government is in the process of evacuating people from low-lying areas in 12 districts including 6 coastal ones due to the approaching super cyclonic storm.
8. The impending cyclone has forced the Indian Railways to divert the route for its Bhubaneswar-New Delhi-Bhubaneswar AC Special trains running from Bhubaneswar between May 19 and 22.
9. Prime Minister Narendra Modi will also discuss the super cyclonic storm in a high-level meeting on Monday to review the situation and preparedness.