HEAT INDEX (Syllabus: GS Paper 1 – Geography)

News-CRUX-10     8th September 2023        
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Context: Recently, Iran recorded a scorching heat index of 70 degrees Celsius (°C) in the coastal part of the country, a metric at which survival of life is unfathomable, if not impossible.

Heat Index

  • About: Heat index, also known as apparent temperature, is a measure of how the temperature feels to humans.

         o Relative humidity is an important factor that determines heat index, along with air temperature.

  • Calculation: A complex formula to calculate heat index was published by Dr. Robert Steadman in 1979. Different countries have developed their own corresponding indices.

        o In 2024, India is scheduled to launch its own heat index.

        o The air temperature and the relative humidity readings are needed to determine the heat index.

  • Significance: It is more useful than just the temperature to gauge the impact of heat on humans.

         o A heat index value of 67°C or above can be extremely dangerous for people and animals who have direct and prolonged exposure.

Relative humidity (RH): It is a measure of the amount of moisture or water vapor present in the air compared to the maximum amount of moisture that the air can hold at a specific temperature and pressure.