Heat Index

 About Heat index:

• Heat index is a measure of how hot it feels when humidity is factored in along with the air temperature, and the figures were calculated using data from the India Meteorological Department (IMD).
• It is also known as the apparent temperature.
• 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. 
• In other words, 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). 

Q1) Meteorological Department What does it do?

To take meteorological observations and to provide current and forecast meteorological information for optimum operation of weather-sensitive activities like agriculture, irrigation, shipping, aviation, offshore oil explorations, etc

Source: India to launch its own heat index next year to quantify heat hazard, generate impact-based heat wave alerts for specific locations

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