Article 3: Tropical Cyclones: Formation, Impacts and Disaster Management
Why in news: The India Meteorological Department forecast that the very severe cyclonic storm would cross the Andhra Pradesh–Yanam coast between Bapatla and Visakhapatnam on 28 October, with sustained winds of 115–125 kmph.
Key Details
- Formation: Tropical cyclones develop over warm oceans, generally above 26.5°C, and derive energy from latent heat released during condensation.
- Formation Conditions: Warm ocean water, high humidity, atmospheric instability, the Coriolis force, low vertical wind shear and a pre-existing low-pressure disturbance support cyclone development.
- Structure and Movement: Cyclones consist of an eye, eyewall and spiral rainbands. They rotate anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
- Regional Names: They are called hurricanes in the Atlantic and eastern North Pacific, typhoons in the northwestern Pacific, and cyclones in the Indian Ocean and South Pacific.
- Impacts and Management: Strong winds, storm surges and heavy rainfall cause widespread damage. Early warnings, timely evacuation, cyclone shelters, resilient infrastructure and mangrove conservation help reduce disaster losses.
Meaning and Formation
- Tropical cyclones are intense low-pressure systems that develop over warm tropical oceans.
- They derive their energy mainly from the latent heat released during the condensation of water vapour.
- They generally form over ocean waters with temperatures of 26.5°C or higher.
- Warm, moist air rises and creates a low-pressure area. Surrounding air moves towards this area, leading to the development of strong winds and thunderstorms.
- As the system intensifies, it develops a rotating circulation around its centre.
Conditions Required for Formation
- Warm ocean water: Provides heat and moisture that fuel the cyclone.
- High humidity: Supplies sufficient water vapour for cloud formation and condensation.
- Atmospheric instability: Encourages warm air to rise and supports thunderstorm development.
- Coriolis force: Helps organise the rotation of the cyclone. It is weak near the Equator, so cyclones rarely form within about 5° latitude of it.
- Low vertical wind shear: Allows the storm to develop vertically without being disrupted by strong changes in wind speed or direction with height.
- Pre-existing low-pressure disturbance: Provides the initial centre around which the cyclone can develop.
Structure of Tropical Cyclones
- Eye: The central region with the lowest pressure, generally light winds and relatively clear skies.
- Eyewall: A ring of intense thunderstorms surrounding the eye, where the strongest winds and heaviest rainfall occur.
- Spiral rainbands: Bands of clouds and thunderstorms extending outward from the eyewall, producing heavy rainfall and gusty winds.
- Warm core: Tropical cyclones have a warm central core due to the release of latent heat during condensation.
- Pressure gradient: The pressure difference between the centre and surrounding areas contributes to the development of strong winds.
Movement and Regional Names
- Tropical cyclones rotate anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemispheredue to the Coriolis effect.
- They generally move under the influence of large-scale atmospheric winds and may change direction during their development.
- They are called hurricanes in the Atlantic Ocean and eastern North Pacific.
- They are called typhoons in the northwestern Pacific and cyclones in the Indian Ocean and South Pacific.
- Tropical cyclones generally weaken over land or cooler waters because their supply of heat and moisture decreases. Strong vertical wind shear can also weaken them.
Impacts and Disaster Management
- Strong winds: Damage buildings, power lines, communication networks and transport infrastructure.
- Storm surges: Raise sea levels near the coast and cause severe coastal flooding.
- Heavy rainfall: Triggers floods, landslides, soil erosion and damage to agricultural land.
- Socio-economic impacts: Cause loss of life, displacement, livelihood disruption and damage to fisheries and coastal industries.
- Early warning systems: Satellite monitoring, Doppler weather radars and timely forecasts help authorities prepare for approaching cyclones.
- Preparedness and mitigation: Evacuation plans, cyclone shelters, resilient infrastructure, mangrove conservation and coordinated disaster response help reduce loss of life and property.
Conclusion
Tropical cyclones are recurring hazards for India’s coastal regions, threatening lives, livelihoods and infrastructure. Although advances in forecasting and early warnings have improved disaster response, economic losses remain a concern. India must strengthen coastal resilience through timely evacuation, cyclone-resistant infrastructure, ecosystem restoration and community preparedness. An integrated approach combining technology, institutional coordination and local participation is essential for sustainable disaster risk reduction.
Descriptive question:
Tropical cyclones pose serious risks to India’s coastal regions. Discuss the conditions responsible for their formation, their major impacts, and the measures required to strengthen India’s cyclone disaster management. (150 words, 10 marks)
Source: The Indian Express