What are Heatwaves , how are they defined

  May 21, 2022

What are Heatwaves , how are they defined

Q. Why is this in news?

A. India is gripped in the wrath of a long spell of heatwaves that too in the early month of April.

Q. What is a Heatwave and when is it declared?


Q. How are they formed?


Q. What are the criteria used to declare heatwave?

A. To declare heatwave, the below criteria should be met at least in 2 stations in a Meteorological subdivision for at least two consecutive days and it will be declared on the second day.

  1. a) Based on Departure from Normal
  1. b) Based on Actual Maximum Temperature (for plains only)

Q. How long can a heatwave spell last?


Q. What are the Impact of Heat Waves?

Heat Strokes: The very high temperatures or humid conditions pose an elevated risk of heat stroke or heat exhaustion.

Older people and people with chronic illness such as heart diseaserespiratory disease, and diabetes are more susceptible to heatstroke, as the body’s ability to regulate heat deteriorates with age.

Increased Healthcare Costs: Effects from extreme heat are also associated with increased hospitalisations and emergency room visits, increased deaths from cardio-respiratory and other diseases, mental health issues, adverse pregnancy and birth outcomes, etc.

Lessens Workers’ Productivity: Extreme heat also lessens worker productivity, especially among the more than 1 billion workers who are exposed to high heat on a regular basis. These workers often report reduced work output due to heat stress.

Risk of Wildfires: The heat domes act as fuel to wildfires, which destroys a lot of land area every year in countries like the US.

Prevents Cloud Formation: The condition also prevents clouds from forming, allowing for more radiation from the sun to hit the ground.

Effect on Vegetation: The trapping of heat can also damage crops, dry out vegetation and result in droughts.

Increased Energy Demands: The sweltering heat wave also leads to rise in energy demand, especially electricity, leading to pushing up rates.

Power Related Issues: Heat waves are often high mortality disasters.

Avoiding heat-related disasters depends on the resilience of the electrical grid, which can fail if electricity demand due to air conditioning use exceeds supply.

As a result, there is the double risk of infrastructure failure and health impacts.