Powerful Tropical Cyclones: Winds, Pressure, and Heat

Tropical cyclones are intense low-pressure areas confined to the area lying between 30°N and 30° S latitudes, in the atmosphere around which high-velocity winds blow. Horizontally, it extends up to 500-1,000 km and vertically from the surface to 12-14 km. 

It 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.

Key points about tropical cyclones: Formation, Impact, and Mitigation in India

• Condition for Formation for tropical cyclone: Heat, Air, and Forces
  • Temperature: Warm sea surface temperature above 27 degrees Celsius.
  • Supply of Warm Air: Large and continuous supply of warm and moist air that can release enormous latent heat.
  • Coriolis force: Strong Coriolis force that can prevent the filling of low pressure at the centre (absence of Coriolis force near the equator prohibits the formation of tropical cyclones between 0°-5°°latitude).
  • Unstable Condition: Catalyst for Cyclone Development
    • Through the troposphere that creates local disturbances around which a cyclone develops.
    • Absence of strong vertical wind wedge, which disturbs the vertical transport of latent heat.

Stages of Cyclone Formation

Spatio-temporal Distribution of Tropical Cyclones in India: Geography, Seasons, and Coastal Impact

• Geographical Influence: Owing to its Peninsular shape surrounded by the Bay of Bengal in the east and the Arabian Sea in the west, the tropical cyclones in India originate in these two important locations. 
  • Cyclonic Storms in Coastal Areas: The coastal areas are often struck by severe cyclonic storms with an average velocity of 180 km/h.
  • Monsoonal Origins: Most of the cyclones originate between 10°-15°north latitudes during the monsoon season.
  • Bay of Bengal Cyclone Season: However, in the case of the Bay of Bengal, cyclones mostly develop during the months of October and November. 
    • Here, they originate between 16°-2° N latitudes and to the west of 92° E. 
    • By July the place of origin of these storms shifts to around 18° N latitude and west of 90°E near the Sunderban Delta.

Wind and Cyclone Hazard Zones

Consequences of Tropical Cyclones: Devastation and Aftermath

• Sudden, brief onslaught, high winds cause major damage to infrastructure and housing.
• Storm Surge: It is an abnormal rise in the sea level. It results in inundation of human settlements, and agricultural fields.
• Contamination of Water: Ground and pipe water supply may get contaminated by flood waters.
• Ruin of Crops: High winds and rains ruin the standing crops and food stock lying in low-lying areas.
  • Salt from the seawater may get deposited on the agricultural land and increase the salinity.
  • The loss of the crop may lead to acute food shortage.
• Damage to Infrastructure: Disruption in the communication links as the wind may bring down the electricity and communication towers.
  • Transport lines (road and rail) may be curtailed, Lack of proper communication affects the effective distribution of relief materials.

Risk Reduction Measures: Strategies for Resilient Communities

• Coastal belt Plantation: Act as a wide buffer zone against strong winds and flash floods.
• Hazard Mapping: A hazard map will show areas vulnerable to cyclones. It will be useful for disaster risk preparedness.
• Good Construction Practices (Refer Figure) should be adopted such as:
  • All elements holding the structures need to be properly anchored to resist the uplift or flying off of the objects.
  • A row of planted trees will act as a shield. It reduces the energy.
  • Buildings should be wind and water-resistant.
  • Buildings storing food supplies must be protected against the winds and water.
  • Communication lines should be installed underground.
  • Provide strong halls for community shelter in vulnerable locations.

Safe Construction Practices

Thus, Understanding the nature of tropical cyclones and implementing effective preparedness, early warning systems, and infrastructure development are critical in reducing the risks associated with these powerful storms.

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