North India is experiencing a severe cold wave, with temperatures plunging below freezing levels in some areas.
The weather department has already issued a cold wave warning in numerous Indian states and union territories, including Delhi, Haryana, and Rajasthan. All of these states have experienced a considerable dip in temperature during the last few days.
Cold wave to severe cold wave conditions are expected to persist in various states and union territories this week, according to the Indian Meteorological Department (IMD). For the next few days, states like Delhi, Rajasthan, and Madhya Pradesh are anticipated to see bitterly chilly temperatures.
Between December 22 and 25, two Western Disturbances are expected to bring light to moderate rainfall and snowfall to the western Himalayan region, according to IMD.
Meanwhile, netizens used the hashtag #coldwave to highlight winter fashion and seasonal treats on social media; others even joined in by sharing relatable jokes about typical challenges, such as bathing in the winter or simply getting out of blankets.
The minimum temperature recorded by a meteorological station on the plains must be 10 degrees Celsius or less - for high-altitude hills, the minimum must be below or at 0 degrees - and the highest temperature must be 4.5-6.4 degrees Celsius below normal, according to the IMD. A ¡®severe cold day¡¯ occurs when the maximum decreases by 6.5 degrees or above the normal.
Then there is the ¡®cold wave¡¯ which, according to the National Disaster Management Authority (NDMA), ¡°is distinguished by a well-defined and protracted period of lower temperatures" and is an extreme weather phenomenon that prominently occurs between the months of November and February.?
The cold wave is defined by the rate at which the temperature drops and the lowest point to which it drops, which varies depending on the geographical region and time of year. A cold wave, according to the IMD, is defined as a quick drop in temperature across a vast area accompanied by "a considerable cooling of the air, or the invasion of very cold air."?
As the cold wave hit, people in northern India would have noted the chilly winds sweeping the country, as well as the significant drop in temperature. Cold waves are linked to "transient disturbances in the mid-latitude westerlies" in the northern sections of India, particularly the hilly regions and adjacent plains, according to the NDMA.?
The "main elements," according to NDMA, are "A build-up of a ridge, or a protracted area of relatively high atmospheric pressure," in the jet stream across northwest Asia is one of the causes of cold waves in India.
Jet streams are narrow bands of high wind that travel across the globe from west to east. A triggering mechanism "like a strong westerly breeze approaching northwest India". Moreover, the vast snow cover in the northwest Himalayas also contributes to the formation of a cold wave.
Experts claim that during the winter months, the passage of western disturbances causes "dry, cold north-westerly winds" to blow into north and central India, causing minimum temperatures to plummet over these areas, resulting in cold-wave conditions. According to studies, a western disturbance occurs when moisture-laden winds replace chilly and dry northwesterly winds with warm and wet easterly breezes.
Furthermore, winds flowing in from the west are known as westerlies. These are the ones that are heavily influenced by the 'La Nina' weather phenomenon.
Cold weather has arrived early this year, raising fears of a harsh winter as bitter winds blow in from the northwest. This indicates that the La Nina effect is lowering temperatures. This phenomena, which originates in the eastern Pacific, is linked to the subcontinent's cooler winters.
The phrase "La Nina," which means "the girl" in Spanish, refers to the winds that blow over the Pacific Ocean and cause changes that affect people all around the world. In normal times, winds over the Pacific Ocean gently flow warm water west, from the west coast of South America to Indonesia, according to the US National Oceanic and Atmospheric Administration (NOAA). As the warm water moves, cold water from the ocean's depths rises to fill the void.
However, La Nina and its polar opposite, El Nino (Spanish for "small boy"), "disrupt these typical conditions." La Nina, the cooling phase of the phenomena known as El Nino Southern Oscillation (ENSO), causes stronger winds above the Pacific Ocean, causing more warm ocean water to be pushed west toward Indonesia than usual, resulting in more cold water coming to the surface near South America.
However, this modest difference in ocean temperatures is enough to cause a global change in weather, with below-normal temperatures in the northern hemisphere being one of the consequences. La Nina can cause an increase in moisture over the Indian subcontinent, resulting in an abundance of snowfall and rainfall.
While "weak La Nina conditions are prevailing over the equatorial Pacific region" at the moment, the forecast indicates that "La Nina conditions are likely to strengthen and peak to moderate conditions during the upcoming winter season," according to IMD's seasonal outlook for winter temperatures released on December 20.
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