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Frequency Of Heatwave Increases

Frequency Of Heatwave Increases:

India Meteorological Department (IMD) has predicted an increase in the maximum temperature and the frequency of heatwave conditions in the forthcoming days over eastern and southern India.

  • Heat wave is a condition of air temperature which becomes fatal to human body when exposed.
  • It is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal.
  • The IMD will declare a heatwave:
    • if the maximum temperature recorded at a station is 40 degrees Celsius or more in the plains, 37 degrees Celsius or more in the coast, and 30 degrees Celsius or more in the hills.
    • a heatwave’s severity is determined by its departure from normal temperature.
    • there is a ‘normal heatwave’ when the departure is by 4.5-6.4 degrees Celsius and a ‘severe heatwave’ if the departure is greater.
  • Heat wave declaration could also be based on actual maximum temperature:
  • A ‘heatwave’ is when this figure is greater than 45 degrees Celsius and a ‘severe heatwave’ when greater than 47 degrees Celsius.
  • The IMD takes these two ‘routes’ only when at least two stations in a meteorological subdivision report such a high maximum or when at least one station has recorded a corresponding departure from the normal for at least two consecutive days.