New Delhi: Winters have finally ringed in, and most of north India is already covered in snow. As the North shivers, the South continues to battle rain. The India Meteorological Department (IMD) has issued a warning that cold wave conditions will continue to prevail in parts of north India this weekend.
Cold wave conditions in parts of Punjab and Uttar Pradesh are expected to remain until December 15. But what is a cold wave, when does it occur, and how is it measured? Let’s read on to learn more.
Understanding India’s Cold Wave: Definition and Criteria
Definition
According to Merriam-Webster Dictionary, cold wave means
1) A huge and rapid drop in temperature over a short period (such as 24 hours).
2) A permanent wave set by a chemical preparation without the use of heat.
How is the Cold Wave defined in India?
A cold wave occurs when the temperature drops quickly within 24 hours. It is defined as a minimum temperature of 10 degrees Celsius or lower, which is also 4.5 degrees Celsius below normal for two consecutive days in the plains. This sudden drop in temperature requires extra care for farming, industry, commerce, and social activities.
A “severe” cold day occurs when the maximum temperature is at least 6.5 degrees below normal.
Coastal areas rarely reach a minimum temperature of 10 degrees Celsius. However, local people may feel uncomfortable due to the wind chill, which makes the air feel colder based on how fast the wind blows. The wind chill factor measures how much the wind cools the air temperature.
Criteria for Cold Wave/Severe Cold Wave
a) When the normal minimum temperature of the station is 10 degrees C or more
Nomenclature
Departure from Normal Temperature
Normal
-1 degree C to 1 degree C
Below Normal
-2 degree C
Appreciably Below Normal
-3 to -4 degree C
Markedly Below Normal/Moderate Cold wave
-5 to -6 degree C
Severe Cold Wave
-7 degree C
b) When the normal maximum temperature of the station is less than 100C (The term moderate cold wave will not be used)
Nomenclature
Departure from Normal Temperature
Normal
-1 degree C to 1 degree C
Below Normal
-2 degree C
Cold Wave
-3 to -4 degree C
Severe Cold Wave
-5 degree C or less
Source: India Meteorological Department (IMD)
What are India’s Core Cold Wave Zones?
India’s ‘core cold wave zone’ covers Delhi, Punjab, Himachal Pradesh, Uttarakhand, Haryana, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha and Telangana.
Causes and Impact of Cold Waves
No Cloud Cover in the Area.
Due to snowfall, cold winds from the upper Himalayas have started blowing into the region.
Cold air descends in the Area, meaning cold and dry air is moving closer to the ground.
La Nina conditions are occurring in the Pacific Ocean. La Nina means the sea temperatures along the equator are cooler than usual, which can lead to cold waves in our region.
Western disturbances are weather systems that move east from the Mediterranean Sea. They bring cold winds, precipitation, and cloud cover to northwest India. These disturbances can lower temperatures and create cold wave conditions.
Health Risks Associated with Cold Wave Conditions
Cold waves can severely affect human health. They can cause coughs, colds, bronchitis, and respiratory diseases. Due to a lack of sunlight, people may also experience blood pressure problems, skin issues, and pain in bones, joints, and muscles. The health of poor people is particularly at risk, and in extreme cases, these conditions can even lead to death.
A cold wave is a minimum temperature of 10°C or 4.5°C below normal for two consecutive days. Severe cold wave conditions pose significant health risks, particularly for vulnerable populations, potentially leading to respiratory illnesses and other complications. knowledge Knowledge News, Photos and Videos on General Knowledge
