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Heat Index

2023 JUL 21

Preliminary   > Disaster Management   >   Disasters   >   Disaster risk reduction

Why in news?

  • India Meteorological Department (IMD) has launched the Heat Index on an experimental basis.

About Heat Index:

  • Heat Index will calculate the temperature along with the humidity levels to provide a more accurate measure of what the temperature actually feels like.
  • In the US, the heat index is color-coded to provide warnings based on the impact of the heat index. The IMD is planning to introduce a similar color-coded warning system in India.


  • Heat Index has important considerations for the human body's comfort.
  • When the body gets too hot, it begins to perspire or sweat to cool itself off. If the perspiration is not able to evaporate, the body cannot regulate its temperature. Evaporation is a cooling process. When perspiration is evaporated off the body, it effectively reduces the body's temperature.
  • When the atmospheric moisture content (i.e., relative humidity) is high, the rate of evaporation from the body decreases. The human body feels warmer in humid conditions. The opposite is true when the relative humidity decreases because the rate of perspiration increases. The body actually feels cooler in arid conditions.
  • There is direct relationship between the air temperature and relative humidity and the heat index, meaning as the air temperature and relative humidity increase (decrease), the heat index increases (decreases).


Which of the following factors are considered for Heat Index of India by Meteorological Department (IMD)? 

(a) Atmospheric pressure and temperature

(b) Air temperature and relative humidity

(c) Solar radiation and atmospheric pressure

(d) Relative humidity and solar radiation