With the recent news that heat waves in India are increasing due to climate change, heat waves will become more intense and frequent in the future. Experts warned on Thursday that governments must take immediate action to prevent more significant effects on public health and food security.
However, what are heat waves? Here is an explanation of what the phenomenon is!
What is a heat wave?
A heat wave is a situation of air temperature that, when experienced by a person, is lethal. It is quantified based on the temperature thresholds that apply to a location in terms of the actual temperature or the deviation from the norm. In some nations, the phrase denotes the heat index, which is based on temperature and humidity or the extreme percentile of temperatures.
How is a heat wave measured?
Regardless of the usual maximum temperature, the IMD states that heat waves in India are proclaimed when the actual maximum temperature hits 45 degrees Celsius or above. Heat waves are announced in plains when the temperature hits at least 40 degrees Celsius, whereas they are declared in mountainous regions when the temperature exceeds 30 degrees Celsius.
A heat wave is a deviation from the average temperature of 5 to 6 degrees Celsius for areas where the average maximum temperature is less than or equal to 40 degrees Celsius. A severe heat wave is a deviation of 7 degrees Celsius or more.
A heat wave is a deviation from the average temperature of 4 to 5 degrees Celsius for areas where the average maximum temperature is greater than 40 degrees Celsius. A severe heat wave is a deviation of 6 degrees Celsius or more.
What is a heat wave period in India, and which states are prone to it?
Heat waves in India mostly happen from March through June, with a few uncommon instances occurring in July. May is when the heat wave in India reaches its height. From March to June, heat waves frequently affect the plains of northwest India, Central, East, and North Peninsular India. It includes portions of Maharashtra, Karnataka, Andhra Pradesh, and Telangana. It also occurs in Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, Jharkhand, West Bengal, Odisha, Madhya Pradesh, Rajasthan, and Gujarat.
It can also happen occasionally in Kerala and Tamil Nadu. Heat waves in India negatively impact human and animal lives. However, in May, regions in Rajasthan and Vidarbha had maximum temperatures exceeding 45°C.
How does the IMD monitor heat waves?
In order to measure different metrological factors like temperature, relative humidity, pressure, wind speed and direction, etc., IMD has an extensive network of surface observatories that span the entire nation. In order to determine the typical maximum temperature of the day for a particular station, a climatology of maximum temperature for the period 1981–2010 is created based on daily maximum temperature station data. IMD then proclaimed a heat wave over the area according to their definition.
How does the IMD predict heat waves in India?
IMD forecasts heat waves in India based on synoptic analysis of various meteorological parameters and consensus advice from various regional & global numerical prediction models like WRF, GFS, GEFS, NCUM, UMEPS, UM Regional, etc. that are operated by the Ministry of Earth Sciences (MoES) and other international models that are accessible under bilateral multi-institutional agreements.