What is Heat Wave?
26-08-2023
01:17 PM
1 min read
What’s in today’s article?
- Why in News?
- What is Heat wave?
- What is Criterion for Declaring Heat wave?
- How India Meteorological Department (IMD) Monitors the Heat wave?
- How Does Heatwave Affect Human Body?
- How to Avoid Heat Stroke?
Why in News?
- Amid heatwave deaths being reported in parts of the country, Union Health minister Mansukh Mandaviya held a meeting with senior officials of the India Meteorological Department, National Disaster Management Authority, and the Health ministry.
What is Heat wave?
- Qualitatively, heat wave is a condition of air temperature which becomes fatal to human body when exposed.
- Quantitatively, it is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal.
- In certain countries it is defined in term of the heat index based on temperature and humidity or based on extreme percentile of the temperatures.
What is Criterion for Declaring Heat wave?
- Heat wave is considered if maximum temperature of a station reaches at least 400C or more for Plains and at least 300C or more for Hilly regions.
- For coastal regions –
- When maximum temperature departure is 4.50C or more from normal, Heat Wave may be described provided actual maximum temperature is 370C or more.
- Period of Heat wave over India –
- It is occurring mainly during March to June and in some rare cases even in July. The peak month of the heat wave over India is May.
- Heat wave prone areas of India –
- Heat wave generally occurs over plains of northwest India, Central, East & north Peninsular India during March to June.
How India Meteorological Department (IMD) Monitors the Heat wave?
- IMD has a big network of surface observatories covering entire country to measure various metrological parameters like Temperature, Relative humidity, pressure, wind speed & direction etc.
- Based on daily maximum temperature station data, climatology of maximum temperature is prepared for the period 1981-2010 to find out normal maximum temperature of the day for particular station.
- Thereafter, IMD declared heat wave over the region as per its definition.
How Does Heatwave Affect Human Body?
- We all feel drained and tired after stepping out on an extremely hot day.
- This is referred to as heat exhaustion, which happens when the body sweats excessively to keep the core temperature low.
- A heat stroke happens when the ambient temperature is so high that the body is unable to sweat to regulate the core temperature, which shoots up to 400C.
- In these cases, there is a severe imbalance of salts such as sodium and potassium in the body.
- The high core temperature coupled with salt imbalances disrupts organs, leading to a host of symptoms.
- It can affect the brain, making a person foggy, drowsy, and in severe cases may also lead to a person going into a coma.
- It can lead to kidney and liver damage as well. A cascade of such symptoms leads to death due to heat stroke.
How to Avoid Heat Stroke?
- The primary aim should be to bring down the core temperature of the body fast.
- This can be done by pouring cold water over the person, making them drink cold drinks, and giving them electrolytes to balance salt levels.
- To prevent heat stroke, it is better to avoid stepping out in direct sunlight, especially between noon and 3 pm. You should avoid strenuous activity during this time.
Q1) What is a heat dome?
A heat dome is caused when atmosphere traps hot ocean air, as if bounded by a lid or cap. Heat domes happen when strong high pressure atmospheric conditions combine with the influence of a La Niña.
Q2) What do you mean by temperature inversion?
A temperature inversion is a layer in the atmosphere in which air temperature increases with height.
Source: Heatwave deaths: Why a heat stroke kills, and how to stay safe | IMD