Cold wave conditions in the national capital as the Safdarjung weather station recorded a minimum temperature of 1.9 degrees Celsius on Sunday, 8 January. This is the second-lowest minimum temperature recorded in January from at least 2008.
The cold wave is expected to continue for at least two days more, with many parts of north India expected to face severe cold wave conditions in the coming days.
What causes a cold wave? How much colder is it likely to get? And will we experience a further dip in temperatures to a 'severe cold wave'?
Cold Wave Across North India – What Causes It and How Can You Stay Safe?
1. What Is a Cold Wave?
A cold wave, cold spell, cold snap, or Arctic Snap, is a cooling of the air, caused by a range of factors.
The IMD, however, defines a cold wave in the plains of north India as a dip in minimum temperature to 4.5°C, with overall temperature dropping to under 10°C. In the hills, a cold wave is only declared when temperatures touch 0°C.
In Delhi, Rajasthan, Punjab, Haryana, UP, and Chandigarh, temperatures reached cold wave levels on Saturday and have continued till Monday, as of this report. They're expected to continue with no change for another two days at least.
If the temperature in the plains falls further, to 2°C, or a mean average of below 6.4°C, the IMD declares it a 'severe cold wave'.
According to the IMD, a severe cold wave is air temperature that can become "lethal to the human body when exposed.”
Parts of Punjab, north Rajasthan, and Haryana are expected to face severe cold waves in the coming days. Temperatures are expected to rise by 2-3°C by the end of December, the IMD said on Christmas. However, east India will witness a further drop in temperatures by 2-3°C, after this rise.
Many parts of north India are likely to face a cold wave in the coming days, till 4 January, especially Punjab, Haryana, and Himachal Pradesh, according to the IMD.
Expand2. What Causes a Cold Wave?
A variety of factors can lead to a cold wave. They include:
Pressure differences: According to the National Disaster Management Agency, a "protracted area of relatively high atmospheric pressure" in the jet stream in northwest Asia could result in a cold wave in India. Jet streams occur because the Earth is heated unevenly, and the pressure differences in different areas leads to wind blowing from one to the other.
Cloud cover: Cloud cover, or more accurately, a lack thereof, can lead to a cold wave. Infrared radiation from the Earth is trapped by clouds, and with a decrease in cloud cover, more heat escapes from the Earth's surface, leading to a cooler surface and lower temperatures.
La Niña: La Niña is a weather pattern that occurs in the Pacific Ocean. Warm water floats above cold water. La Niña, which is Spanish for 'little girl', is a weather disruption which leads to these warm waters being blown towards Indonesia. This, in turn, leads to cold water rising to the surface.
This rise in surface cold water leads to a cooling effect. According to the IMD, La Niña is likely to continue from December to February 2023.
Non-seasonal rainfall: Non-seasonal or non-monsoon rainfall is another major cause of cold waves. Like we discussed in the past, the unpredictability of precipitation is only intensifying on the back of climate change. This leads to a decrease in monsoon rainfall (when it benefits agriculture in India), and an increase in off-season rainfall. One of the many fallouts of this is increased cold waves in the winter months.
Expand3. What Precautions Should You Take During a Cold Wave?
The IMD issued a set of precautions to follow in the coming days including a warning that instances of flu, runny nose, and nosebleeds would be even more likely because of prolonged exposure to cold. It adds:
Don't ignore shivering. Stay indoors and stay warm as far as possible.
Your body's core temperature hovers at around 36.8 - 37.5°C. If you lose too much heat from your core, you run the risk of hypothermia, and in the worst case, frostbite.
Frostbite leads to your extremities turning blue or pale from a lack of circulation. As blood rushes to your core to maintain your internal temperature, your fingers, toes, nose, and earlobes turn cold, and this can VERY quickly lead to a life-threatening emergency.
If outdoors, wear several layers of loose, comfortable, warm clothing to retain your core temperature and keep yourself warm. This includes wearing several layers of lightweight, warm, wool clothing.
Avoid staying wet, and if you do get wet, change into dry clothes immediately. If you suspect you may be suffering from frostbite, slowly warm the affected area with lukewarm water, avoid rubbing the skin, and speak to a medical professional as soon as possible.
Other ways to keep your core temperature warm include eating adequate amounts of nutritious fat, some vegetables, fruits, and other foods that are rich in energy. The thermic effect of fat and other foods will help you keep your core temperature up.
If you're using a heater indoors, ensure you allow it adequate ventilation, to avoid inhaling any potentially deadly fumes.
(At The Quint, we question everything. Play an active role in shaping our journalism by becoming a member today.)
Expand
What Is a Cold Wave?
A cold wave, cold spell, cold snap, or Arctic Snap, is a cooling of the air, caused by a range of factors.
The IMD, however, defines a cold wave in the plains of north India as a dip in minimum temperature to 4.5°C, with overall temperature dropping to under 10°C. In the hills, a cold wave is only declared when temperatures touch 0°C.
In Delhi, Rajasthan, Punjab, Haryana, UP, and Chandigarh, temperatures reached cold wave levels on Saturday and have continued till Monday, as of this report. They're expected to continue with no change for another two days at least.
If the temperature in the plains falls further, to 2°C, or a mean average of below 6.4°C, the IMD declares it a 'severe cold wave'.
According to the IMD, a severe cold wave is air temperature that can become "lethal to the human body when exposed.”
Parts of Punjab, north Rajasthan, and Haryana are expected to face severe cold waves in the coming days. Temperatures are expected to rise by 2-3°C by the end of December, the IMD said on Christmas. However, east India will witness a further drop in temperatures by 2-3°C, after this rise.
Many parts of north India are likely to face a cold wave in the coming days, till 4 January, especially Punjab, Haryana, and Himachal Pradesh, according to the IMD.
What Causes a Cold Wave?
A variety of factors can lead to a cold wave. They include:
Pressure differences: According to the National Disaster Management Agency, a "protracted area of relatively high atmospheric pressure" in the jet stream in northwest Asia could result in a cold wave in India. Jet streams occur because the Earth is heated unevenly, and the pressure differences in different areas leads to wind blowing from one to the other.
Cloud cover: Cloud cover, or more accurately, a lack thereof, can lead to a cold wave. Infrared radiation from the Earth is trapped by clouds, and with a decrease in cloud cover, more heat escapes from the Earth's surface, leading to a cooler surface and lower temperatures.
La Niña: La Niña is a weather pattern that occurs in the Pacific Ocean. Warm water floats above cold water. La Niña, which is Spanish for 'little girl', is a weather disruption which leads to these warm waters being blown towards Indonesia. This, in turn, leads to cold water rising to the surface.
This rise in surface cold water leads to a cooling effect. According to the IMD, La Niña is likely to continue from December to February 2023.
Non-seasonal rainfall: Non-seasonal or non-monsoon rainfall is another major cause of cold waves. Like we discussed in the past, the unpredictability of precipitation is only intensifying on the back of climate change. This leads to a decrease in monsoon rainfall (when it benefits agriculture in India), and an increase in off-season rainfall. One of the many fallouts of this is increased cold waves in the winter months.
What Precautions Should You Take During a Cold Wave?
The IMD issued a set of precautions to follow in the coming days including a warning that instances of flu, runny nose, and nosebleeds would be even more likely because of prolonged exposure to cold. It adds:
Don't ignore shivering. Stay indoors and stay warm as far as possible.
Your body's core temperature hovers at around 36.8 - 37.5°C. If you lose too much heat from your core, you run the risk of hypothermia, and in the worst case, frostbite.
Frostbite leads to your extremities turning blue or pale from a lack of circulation. As blood rushes to your core to maintain your internal temperature, your fingers, toes, nose, and earlobes turn cold, and this can VERY quickly lead to a life-threatening emergency.
If outdoors, wear several layers of loose, comfortable, warm clothing to retain your core temperature and keep yourself warm. This includes wearing several layers of lightweight, warm, wool clothing.
Avoid staying wet, and if you do get wet, change into dry clothes immediately. If you suspect you may be suffering from frostbite, slowly warm the affected area with lukewarm water, avoid rubbing the skin, and speak to a medical professional as soon as possible.
Other ways to keep your core temperature warm include eating adequate amounts of nutritious fat, some vegetables, fruits, and other foods that are rich in energy. The thermic effect of fat and other foods will help you keep your core temperature up.
If you're using a heater indoors, ensure you allow it adequate ventilation, to avoid inhaling any potentially deadly fumes.
(At The Quint, we question everything. Play an active role in shaping our journalism by becoming a member today.)