‘Gulab’ cyclone: An overview on the concept of cyclones

India is a land of diversity, not only demographically but also in the geographical share of natural disasters as well. The north-western region of hot and cold deserts face extreme heat waves and cold waves respectively, not to mention the landslides in the mountainous terrains. The east witnesses heavy rainfall. The central parts of the country receive earthquakes, floods, droughts (oxymoronically!) and frequent dust storms. The monsoon and rising sea levels concern the southern peninsular region with cyclones.

Courtesy: ResearchGate

India’s position in the North Indian Ocean makes it the most vulnerable to getting hit by tropical cyclones (as many as 120 cyclones have hit India since 1950s). The latest happenstance of concern is the Cyclone Gulab, which hit Odisha and Andhra Pradesh, barely four months after ‘Yaas’, says the India Meteorological Department. On average, 2–3 tropical cyclones make landfall in India each year, with about one being a severe tropical cyclone or greater.

What are cyclones: causes and impacts?

As per Britanica Cyclone is “any large system of winds that circulates about a centre of low atmospheric pressure in a counterclockwise direction north of the Equator and in a clockwise direction to the south.” In simpler words, it is a rapid rotating storm originating over tropical (in case of Indian subcontinent) oceans from where it draws the energy to develop. Its diameter is typically around 200 to 500 km, but can reach 1000 km.

Causes:

  • A narrow zone of low pressure stretches across the equator. The winds on the north side of this zone blow from the north-east (the north-east trades) and on the southern side blow from the south-east (south-east trades).
  • The low-pressure area is heated over the warm tropical ocean which leads to the rise of air from this are in discrete parcels, ultimately causing the formation of thunderstorms.
  • This creates a flow of very warm, moist, rapidly rising air, leading to the development of a center of low pressure, or depression, at the surface.
Courtesy: Quora

Impacts:

  • A tropical cyclone brings very violent winds, torrential rain, high waves and, in some cases, very destructive storm surges and coastal flooding.
  • Tropical cyclones above a certain strength are given names in the interests of public safety.

“Many low-lying areas will be inundated in the identified districts. Flash floods are feared in the hilly areas of Odisha’s southern region. Urban pockets in Ganjam and Puri could experience waterlogging due to heavy to very heavy and extremely heavy rainfall in parts,”

IMD Director-General Mrutunjay Mohapatra

Why do certain parts of India receive more damage than others?

  • The Bay of Bengal is more prone to cyclones because of the vast low pressure created by the warm water of the ocean.
  • The Bay of Bengal is like a trough, making it more hospitable for storms to gain force.
  • Moreover, the high sea surface temperature makes matters worse, as they trigger the intensity of the storms.
  • It gets more rainfall with warm air currents around it.
  • There is a constant inflow of fresh warm water from the perineal rivers like Bramhaputra, Ganga which makes it difficult to mix with cooler underwaters.
  • Lack of landmass between the Pacific Ocean and the Bay of Bengal tend cyclonic winds to move into the coastal areas.
  • Another reason for the cyclones in the Bay of Bengal may be the absence of air movements from north-western India towards the Bay in the post-monsoon phase.

What geographical advantage the Arabian sea has?

  • The Arabian Sea is much calm as the stronger winds help dissipate the heat.
  • The lack of constant fresh water helps the warm water to mix with the cool water underneath, reducing the surface temperature.
  • The Arabian Sea enjoys the locational advantage as the winds from the Pacific Ocean encounter the Western Ghats and the Himalayas cutting down on its intensity and sometimes never reaching the Arabian Sea.

What’s being done to manage disasters and prevent damages?

The mitigation measures proposed by the UN-HABITAT  in their booklet are briefly covered below:

  • Hazard mapping : predicting the vulnerable areas affected by the storms.
  • Using an effective implementation of land use planning, the key activities and settlements can be avoided in the most vulnerable areas.
  • Building structures which can withstand the wind forces and prove to mitigate the losses should be built.
  • The cyclone shelters or artificial hills should be put up to help the vulnerable community from cyclones, at national, state and regional level.
  • Flood management becomes necessary in cyclone affected regions as well.
  • The ecologically-efficient mangroves should be planted more. India has 3 per cent of the world’s mangroves cover.
  • Saline embankments like agricultural crops can help protect habitation along coasts.
  • The participation of the community should be ensured by public awareness initiatives by governments and other authorities or institutes.

Some governmental initiatives for cyclone management in India:

  1. National Cyclone Risk Mitigation Project
  2. Integrated Coastal Zone Management (ICZM) Project
  3. Coastal Regulation Zones (CRZ)
  4. IMD’s Colour Coding of Cyclones
    • It is a weather warning that is issued by the IMD to aware people ahead of natural hazards.
    • The four colours used by IMD are Green, Yellow, Orange, and Red.
    • IMD’s DG announced the introduction of a dynamic and impact-based cyclonic warning system in 2020. IMD will work with NDMA, INCOIS and various state governments to successfully introduce this system.

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