A severe cold wave has enveloped North India, with Delhi experiencing its coldest temperatures in years. The India Meteorological Department (IMD) has issued a warning for cold wave conditions over parts of north-western India from 30 December onwards.
Cold wave, heavy snowfall/rainfall, fog, snowstorms etc. have emerged as major weather hazards in recent years affecting different parts of the country. World Meteorological Organization (WMO) indicates that global temperatures are substantially unveiling variations during various seasons and have a large impact on environment, agriculture, health, livestock, livelihoods, socio-economy and other allied sectors.
Cold waves in India:
Normally, in winter months, after passage of western disturbances, dry cold north-westerly winds make way into north & central India. As a result, minimum temperatures drop over the region and sometimes cause cold wave conditions. Cold wave occurs in the month of December-January every year and sometimes extended cold wave events occur from November to February and are limited mostly to northern India. The cold wave is marked by a well-defined and prolonged period of lower temperatures.
Cold wave is a localised seasonal phenomenon prevalent in the country except in southern India. The northern parts of India, specially the hilly regions (Jammu and Kashmir, Himachal Pradesh, Uttarakhand) and the adjoining plains are influenced by transient disturbances in the mid latitude westerlies which often have weak frontal characteristics. States like Punjab, Haryana, Rajasthan, Delhi, U.P., Bihar and Jharkhand are the highly affected. It also includes some met subdivisions of Marathawada, Vidharbha, Saurashtra and Madhya Maharashtra which are affected by cold waves.
Unraveling the Freeze: Why India Faces Intense Cold Waves?
The answer lies in the combination of factors including India’s location, its physiography, presence of Himalayas, inter-continental climatic interactions through surface as well as upper atmospheric winds and inter-oceanic teleconnections.
The continentality of the Northern India on account of being far away from the Ocean make it prone to extreme climatic conditions. During winters, when the Sun shines vertically over the Tropic of Capricorn, North India develops anti cyclonic conditions marked with aridity and low temperatures. This region attracts cold dry winds from the northern and Northwestern areas like Eurasia and Central Asia respectively. Development of low pressure over North Arabian sea during the same time attracts these winds.
The study, published in the journal Weather and Climate Extremes, sheds light on the underlying causes and alarming trends behind the frigid conditions. Massive collection of the cold dry air mass which get collected over the Siberian region, forms the Siberian high pressure region in the North eastern part of Eurasia from November untill February. The study attributed the ongoing cold wave to the intrusion of cold and dry air from the Siberian high, intensified by the persistence of high-latitude weather systems known as Atmospheric blocking. This atmospheric phenomenon leads to the buildup of cold air, causing extreme cold conditions in northern India.
Similarly the role of Sub Tropical Westerly Jet-stream (STWJ) cannot be ignored. The Jetstreams are the circumpolar upper atmospheric circulations which affect the climate and local weather across the world. STWJ is responsible for bringing the moisture from the Mediterranean Sea and the Caspian Sea to the Indian subcontinent. A build-up of a ridge (an extended area of relatively high atmospheric pressure) in the Jetstream over northwest Asia further intensifies the barometric gradient towards India. This phenomenon leads to fog and heavy rainfall in the Northern, Eastern, and North Eastern India further lowering down the temperatures.
In the month of September 2024, the IMD predicted that India is set to experience harsh winters on account of La-Nina. U.S. National Oceanic and Atmospheric Administration in fact called La-Nina this year “spooky”. The La Niña has not emerged as expected. Historically, the La Niña has usually formed during the monsoon or the pre-monsoon period, and it has formed only twice between October and December since 1950. Global forecasts had also predicted its emergence this monsoon. But in December, there remained only a 57% chance of it forming in 2024. It will be weak if it still does but it could affect global weather.
Chilling Consequences
First is Health – the impact of cold waves on human beings can lead to death or injury. Mortality rates show a marked increase in areas with recurrent cold waves. Dense fogs during such times can lead to coughing, eye irritation, lungs disorders and hypothermia. Second, the cold wave and frost is a major factor that influences crop, horticultural plantations/orchard growth and productivity. It can also cause death and injury to livestock. During a cold wave, animals require a higher intake of nutrition which affects the hormonal level and efficiency of production. Third, the cold wave or extreme cold weather affects the transport sector such as airways, river & seaport, roadways, railways, local transport etc. Fourth, Energy or power sector receives too much pressure during extreme winter or cold wave season. During cold wave season, energy consumption rises significantly. Chances of tripping of power lines increase. Fifth, water sector is directly impacted by cold waves as it gets frozen due to extreme low temperature. Due to freezing, water supply may get disrupted. Sixth, tourism bears both positive and negative impacts of cold weather. India receives a large number of tourists in the months of December and January, but extreme cold may also result in less number of tourists as well as additional challenges for the State Government and local administration for their health and safety.
Conclusion
The National Disaster Management Authority (NDMA) has issued specific guidelines to mitigate the effects of cold waves. These include creating public awareness campaigns about health precautions, setting up night shelters for vulnerable populations, ensuring adequate power supply during high demand periods, and preparing farmers with advisories on protecting crops and livestock. Local governments are also encouraged to implement early warning systems and ensure proper coordination for timely response.
By integrating these guidelines with improved infrastructure, policy frameworks, and community engagement, India can better mitigate the impacts of cold waves and safeguard the lives and livelihoods of its people. The emphasis must remain on preparedness, resilience-building, and ensuring that the most vulnerable populations are adequately protected.
References & Credits:
- https://mausam.imd.gov.in/responsive/pdf_viewer_css/met2/Chapter%206/Chapter%206.pdf
- https://ndma.gov.in/sites/default/files/Newsletter-Nov22/images/Coldwave%20article_SSN.pdf
- https://ndma.gov.in/sites/default/files/PDF/Guidelines/Guidelines-on-Cold-Wave-and-Frost.pdf
- https://www.thehindu.com/sci-tech/energy-and-environment/how-does-la-ni%C3%B1a-affect-indias-climate-explained/article68993281.ece
- https://www.downtoearth.org.in/climate-change/why-are-parts-of-the-country-freezing-india-faces-cold-wave-after-a-year-of-breaking-heat-records#:~:text=What%20is%20a%20cold%20wave,at%20least%20two%20consecutive%20days.
