Heat Waves and Heat Index | 01 Aug 2023

Source: PIB

Why in News?

India has witnessed a significant decline in heat-related deaths in recent years, reflecting the country's efforts to combat the adverse effects of heatwaves.

• The India Meteorological Department (IMD) plays a vital role in this endeavor, issuing timely forecasts and warnings to mitigate the impact of severe weather events, including heatwaves.
• Recently, IMD introduced the Heat Index, a valuable tool that considers humidity's influence on temperatures.

What are Heat Waves?

• About:
  • Heat waves are prolonged periods of excessively hot weather that can cause adverse impacts on human health, the environment, and the economy.
  • India, being a tropical country, is particularly vulnerable to heat waves, which have become more frequent and intense in recent years.
  • IMD Criteria for Declaring Heat Wave in India:
    • Heat wave is considered if the maximum temperature of a station reaches at least 40°C or more for Plains and at least 30°C or more for Hilly regions.
      • Based on Departure from Normal:
        • Heat Wave: Departure from normal is 4.5°C to 6.4°C.
        • Severe Heat Wave: Departure from normal is >6.4°C.
      • Based on Actual Maximum Temperature:
        • Heat Wave: When actual maximum temperature ≥ 45°C.
        • Severe Heat Wave: When actual maximum temperature ≥47°C.
• IMD's Initiatives and Tools to Combat Heat Waves:
  • Timely issuance of heat wave forecasts to keep the public informed.
  • Warnings provided to disaster management authorities for necessary preparedness.
  • IMD offers Seasonal outlook and extended range forecast offering additional insights into temperature trends.
  • Daily forecasts for the next five days with real-time updates.
  • Color-coded warnings for severe weather events, including heat waves.
  • Cooperation with National Disaster Management Authority (NDMA) and local health departments for heat action plans.
  • Implementation of plans in vulnerable regions to minimize heat-related risks.

What is Heat Index?

• About:
  • The Heat Index is a parameter that considers both temperature and humidity to calculate the apparent temperature or "feel like" temperature for human beings.
  • It helps in understanding the impact of humidity on high temperatures and how it contributes to human discomfort during hot weather.
  • The Heat Index has been launched on an experimental basis by the India Meteorological Department (IMD).
  • It aims to provide general guidance for regions experiencing higher apparent temperatures causing discomfort to people.
• Indication of Heat Stress:
  • High Heat Index values indicate a greater risk of heat-related stress and health issues.
  • It serves as a warning for potential heat-related illnesses and dangers.
• Categorization of Heat Levels:
  • The Heat Index categorizes the apparent temperature into different levels using color codes:
    • Green: Experimental heat Index less than 35°C.
    • Yellow: Experimental heat Index in the range 36-45°C.
    • Orange: Experimental heat Index in the range 46-55°C.
    • Red: Experimental heat Index greater than 55°C.
• Useful Tool for Public Health:
  • By understanding the Heat Index, individuals and communities can take proactive steps to protect public health during heatwaves.
  • It assists in making informed decisions and formulating heat action plans to ensure the well-being of the population.