The national capital Delhi is freezing under an envelop of dense fog covering several parts of North India on Monday, which has led to the temperature dipping further. At 2.2°C, Delhi is colder than the popular hill stations of Shimla and Mussoorie. The capital has been experiencing a cold day spell consecutively since December 14, 2019 and the severe cold temperature along with dense fog is said to continue for a few more days. However, this extreme low temperature in the region is not an unusual phenomenon as the average maximum temperature in Delhi, for the month of December has been less than 20°C until December 27. The extreme cold phenomenon has happened only four times in the last 118 years. According to the Indian Meteorological Department (IMD), this month will most likely become the second coldest December for the capital since the year 1901. IMD officials have said that December 30 is that coldest recorded December day in Delhi since 1901. The maximum temperatures had averaged to about 17.3°C in the month of December 1901.
According to IMD scientists who were quoted in a recent IE report, there is nothing unusual in the climatic conditions which influence temperatures in the Northern region at this time of the year. The cold waves usually arrive from the western side, through the Western Disturbance wind system. The Western Disturbance is also responsible for causing rains in the northern and northwestern parts, after having picked up moisture on its route from the side of the Mediterranean Sea. The intensity of the cold wave also depends on the amount of snowfall received in areas of Jammu and Kashmir, Himachal Pradesh, Ladakh and nearby hilly areas. All of these factors have annual variabilities and combine in different methods to produce varied types of winter conditions.
R K Jenamani, senior scientist at the IMD's National Weather Forecasting Centre (NWFC) was quoted in the report saying that the formation of low stratus clouds are unique over the Indo-Gangetic Plains (IGP). These low stratus clouds have been observed only since the year 1997 and as these clouds are formed at a height of 300 metres – 400 metres from the surface, they largely block the day's sunlight, resulting in the cold waves. He added that in Delhi, the average maximum temperatures for the month stands around 19.8 degrees until December 27 and with cold days being in forecast till month end, December 2019 could be the second coldest after the year 1997.
However, the impact now could likely be higher than that experienced in 1997. It is important to note that the cold waves during the daytime can be dangerous. The impact of the cold spell in North India can be higher due to climate change. This is because both heat waves and cold waves have increased in the last few years, not just in the country, but across the world.