A woman and child seen in warm clothes on a winter day at Connaught Place in New Delhi on Thursday.(Sanchit Khanna/HT PHOTO)
A woman and child seen in warm clothes on a winter day at Connaught Place in New Delhi on Thursday.(Sanchit Khanna/HT PHOTO)

Chilly spell in Delhi-NCR intensifies, no relief till Dec 21: IMD

Scientists say temperature numbers alone are not able to capture the bitter chill most people are experiencing through the day because the “perception of the temperature” is likely even lower due to the icy cold winds.
Hindustan Times, New Delhi | By Jayashree Nandi, New Delhi
UPDATED ON DEC 18, 2020 04:15 AM IST

The cold spell in Delhi further intensified on Thursday, as the maximum temperature dropped to 15.2 degrees Celsius, seven degrees below normal, which was exacerbated by fast icy winds blowing through the day, leaving city residents shivering.

A departure of seven degrees from normal meant that the India Meteorological Department (IMD) categorised Thursday as a “severe cold day”. This was the fourth consecutive “cold” or “severe cold day”, with weather scientists predicting no relief over the weekend.

Minimum temperature of the day was recorded around 8.30am on Thursday — 4.6 degrees Celsius, four degrees below normal. This means that the gap between maximum and minimum temperature on Thursday was only around 10 degrees Celsius.

Scientists say temperature numbers alone are not able to capture the bitter chill most people are experiencing through the day because the “perception of the temperature” is likely even lower due to the icy cold winds. For example, the “feels like” temperature of Thursday’s minimum temperature is around two-to-three degrees Celsius.

“The ‘feels like’ temperature is much lower because of the icy cold winds that are blowing at 15 to 20 kmph. We don’t expect relief from the bitter cold till December 21. A western disturbance is approaching around that time which will not have much impact on the plains. But the relief will be marginal, an increase of only one-to-two degrees Celsius,” explained Mahesh Palawat, vice-president, climate change and meteorology at Skymet Weather.

The ‘feels like’ temperature takes into account wind speeds and humidity to assess how the human body actually feels temperature. “For example in winter a strong wind can feel much colder than the measured temperature would indicate. Conversely on a humid day in summer it can feel uncomfortably hotter than the air temperatures would suggest on their own,” explains the UK Met Office.

Many stations in northwest India recorded extremely low minimum temperatures on Thursday — Churu recorded 2.2°C; Bikaner 3.1°C; Mt Abu -1°C; Sikar 0.5°C; Bareilly 3.3°C; Delhi Ridge 3.5°C; Narnaul 2.6°C; Ranichauri -1.4°C; and Gulmarg -11°C. Day temperatures were also unusually low — on Wednesday (maximum temperature data has been tabulated for Wednesday) Jammu recorded 14.4°C; Kathua 10; Keylong 3.3; Dalhousie 1.5; Amritsar 8.2; Bathinda 10; Hisar and Karnal at 15; Churu 16; Ganganagar 13.4.

“Icy winds are blowing from the snow-clad mountains towards Delhi now. Around December 15 to 20 climatologically also we see a sharp fall in temperatures as sun rays are falling slightly slanted and not vertical. There is also uplifted fog in some regions over northwest India which is also not allowing the surface to warm up during the day. Overall the icy winds due to heavy snow cover over Himalayas are the primary driver for extremely cold days,” explained Kuldeep Shrivastava, head, regional weather forecasting centre.

IMD had warned on Wednesday that “cold wave” to “severe cold” conditions may have a number of serious impacts on health that shouldn’t be ignored. There is an increased likelihood of various illnesses like flu, stuffy nose or nosebleed, shivering which is a first sign of the body losing heat. Prolonged exposure to extreme cold can cause frostbite, which leads to the skin turns pale, hard and numb and eventually black blisters appear on exposed body parts such as fingers, toes, nose and or earlobes. Severe frostbite needs immediate medical attention and treatment.

The impact-based warning issued by IMD for cold wave recommends that people wear insulated shoes, moisturise skin, increase vitamin C intake, limit outdoor activities, maintain ventilation while using heaters, avoid drinking alcohol as it reduces body heat etc.

Some of those exposed to dense fog could also suffer health impacts. Dense fog contains particulate matter and other pollutants which can get lodged in the lungs leading to episodes of wheezing, coughing and shortness of breath. Those with asthma and bronchitis are particularly vulnerable.

According to IMD, a “cold day” or “severe cold day” is considered based on two parameters — a minimum temperature of under 10 degrees Celsius and maximum temperature that is 4.5 degrees Celsius or 6.4 degrees Celsius below normal respectively.

A cold wave occurs in plains when the minimum temperature is 10 degrees Celsius or below and/or is 4.5 notches lesser than the season’s normal for two consecutive days. Cold wave is also declared when the minimum temperature is less than 4 degree C in the plains. Witnessing a cold day and cold wave together means the gap between day and night temperatures was lower than normal.

“Cold wave to severe cold wave” conditions are very likely in some pockets over Punjab, Haryana, Chandigarh, West Uttar Pradesh and north Rajasthan during next three days and decrease thereafter according to IMD’s bulletin. “Cold day to severe cold day” conditions are likely in some pockets over Punjab, Haryana, Chandigarh and Delhi, north Rajasthan and northwest Uttar Pradesh during next two days and decrease thereafter. Dense fog is likely in some pockets over Assam, Meghalaya, Tripura and Mizoram during next three days.

“There was heavy and widespread snowfall in the Western Himalayas from December 11 to 13 and then dense fog started being recorded in many places which has led to cold day conditions. Due to extremely chilly winds, we have issued an impact-based warning for the first time which tells people what to do during cold wave and cold day conditions,” added RK Jenamani, senior scientist, national weather forecasting centre.

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