Context:

Typhoon In-fa made landfall in China forcing the city of Shanghai and neighbouring coastal regions to cancel all flights and shutter businesses.

Relevance:

GS-I: Geography (Physical geography – Climatology, Important Geophysical phenomena), GS-III: Disaster Management

Dimensions of the Article:

  1. Typhoon In-Fa
  2. Tropical Cyclones and their Structure
  3. Why tropical cyclones don’t form in the eastern tropical oceans?
  4. Landfall: What happens when a Cyclone reaches land from the ocean?

Typhoon In-Fa

  • China’s national observatory renewed its orange or second-highest alert for typhoon In-Fa, which made landfall in Zhejiang province.
  • Typhoon In-Fa is a Tropical Cyclone – Tropical Cyclones are referred to as “Typhoons” in the Western Pacific and the South China Sea.
  • Depending on its location and strength, tropical cyclones are referred to by different names:
    1. Cyclones in the Indian Ocean
    2. Hurricanes in the Atlantic
    3. Typhoons in the Western Pacific and the South China Sea
    4. Willy-willies in Western Australia

Click Here to read about Tropical Cyclones and their Structure

Why tropical cyclones don’t form in the eastern tropical oceans?

  • The depth of warm water (26-27°C) should extend for 60-70 m from surface of the ocean/sea, so that deep convection currents within the water do not churn and mix the cooler water below with the warmer water near the surface.
  • The above condition occurs only in western tropical oceans because of warm ocean currents (easterly trade winds pushes ocean waters towards west) that flow from east towards west forming a thick layer of water with temperatures greater than 27°C. This supplies enough moisture to the storm.
  • The cold currents lower the surface temperatures of the eastern parts of the tropical oceans making them unfit for the breeding of cyclonic storms.
  • ONE EXCEPTION: During strong El Nino years, strong hurricanes occur in the eastern Pacific. This is due to the accumulation of warm waters in the eastern Pacific due to weak Walker Cell.

Landfall: What happens when a Cyclone reaches land from the ocean?

  • Tropical cyclones dissipate when they can no longer extract sufficient energy from warm ocean water.
  • A storm that moves over land will abruptly lose its fuel source and quickly lose intensity.
  • A tropical cyclone can contribute to its own demise by stirring up deeper, cooler ocean waters. tropical cyclone can contribute to its own demise by stirring up deeper, cooler ocean waters.

-Source: The Hindu

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