Unusual February heat, and the ‘normal abnormal’ in global weather
- February 22, 2023
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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Unusual February heat, and the ‘normal abnormal’ in global weather
Subject : Geography
Section: PJUSICAL Geography ( climatology)
Concept :
- It is still February, technically a winter month, and temperatures in some parts of the country are touching 40 degrees Celsius. There are already concerns over the possibility of an intensely hot summer and extended heat waves this year.
- However, the current spell of abnormally high temperatures, mainly in northern and western India, is no indicator of how hot the summer, or the rest of the year will be.
India IMD Weather Forecast:
- The maximum temperature in February, averaged over the country as a whole, is expected to be around 28 degrees C based on the record of the 30-year period from 1981 to 2010. This is taken to be the “normal”. The minimum temperature is expected to be around 15 degrees C.
- However in the past week, maximum temperatures have been 5-11 degrees C higher than normal in most parts of northern and western India.
- These abnormal high temperatures are qualified to be decribed as ‘heat waves’.
- However, heat wave declarations by the IMD, which trigger follow-up action by the local administration, are meant only for the April-July period, not for February or March.
Possible Reasons
- The IMD has attributed the current spell of hot weather to a combination of factors, including the absence of western disturbance activity in February, which brings some rainfall in this month and keeps temperatures down.
- Until now, less than a sixth of the country has recorded normal or excess rainfall for February.
- The IMD has said that the plains have been relatively dry, and rainfall or snowfall in the hills has been subdued.
- According to the IMD, an anticyclonic formation over south Gujarat is one of the main reasons for the warming on the west coast. Its effect was being transmitted northward to Rajasthan, Punjab, Delhi, Himachal Pradesh, and western Uttar Pradesh.
- At the gobal level, this year is widely expected to be a little hotter than the previous two years, mainly because of the expected end of the strongest ever La Niña event.
- The cushion against warming provided by the La Niña is projected to go in the next couple of months, raising fears that this year could set new warming records.
What are heat waves?
- A Heat Wave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western parts of India.
- Heat Waves typically occur between March and June, and in some rare cases even extend till July.
- The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.
- The Indian Meteorological Department (IMD) has given the following criteria for Heat Waves :
- Heat Wave need not be considered till maximum temperature of a station reaches atleast 40°C for Plains and atleast 30°C for Hilly regions.
- When normal maximum temperature of a station is less than or equal to 40°C .
- Heat Wave Departure from normal is 5°C to 6°C and Severe Heat Wave Departure from normal is 7°C or more
- When actual maximum temperature remains 45°C or more irrespective of normal maximum temperature, heat waves should be declared.
- Higher daily peak temperatures and longer, more intense heat waves are becomingly increasingly frequent globally due to climate change.
- India too is feeling the impact of climate change in terms of increased instances of heat waves which are more intense in nature with each passing year, and have a devastating impact on human health thereby increasing the number of heat wave casualties.