Featured image: A newspaper vendor rides a bicycle, in New Delhi, Sunday, November 29, 2020. Photo: PTI/ Manvender Vashist
New Delhi: The November of 2020 was the coldest in the national capital in 71 years, with the mean minimum temperature dropping to 10.2º C, according to the India Meteorological Department.
Delhi had recorded a mean minimum temperature of 10.2º C in November 1949. The mean minimum temperature for November was 9.6º C in 1938; 9º C in 1931 and 8.9º C in 1930, according to IMD data.
Normally, the mean minimum temperature for the month of November is 12.9º C. It was 15º C last year, 13.4º C in 2018 and 12.8º C both in 2017 and 2016.
Also, the month of October this year was the coldest in 58 years in the national capital. The mean minimum temperature in October this year was 17.2º C, the lowest since 1962, when it was 16.9º C.
Delhi also braved four cold waves in November – on the 3rd, 20th, 23rd and 24th. For the plains, the IMD declares a cold wave when the minimum temperature is 10º C or below and is 4.5 notches less than normal for two consecutive days.
“However, for small areas such as Delhi, a cold wave can be declared if the criteria is fulfilled even for a day,” Kuldeep Srivastava, the head of the IMD’s regional forecasting centre, said.
On Monday, Delhi recorded a minimum of 6.9º C. This is the eighth day this month that the minimum temperature remained below 10º C.
On November 23, Delhi recorded a minimum of 6.3º C, which is the lowest in the month since November 2003, when the city recorded a low of 6.1º C, according to Srivastava.
The minimum temperature this month, barring on November 16, has remained 2-3º C below normal in the absence of a cloud cover on most days, according to IMD officials.
Clouds trap some of the outgoing infrared radiation and radiate it back downward, warming the ground.
The prominent wind direction remained westerly-northwesterly on most of the days. These winds blow from snowcapped western Himalayas towards the plains. Another reason for the below-normal temperatures is La Nina, a phenomenon associated with the cooling of Pacific waters and an antithesis to El Nino.
“Currently, Sea Surface Temperatures are below normal over central and eastern equatorial Pacific Ocean and moderate La Ni a conditions are prevailing over the equatorial Pacific Ocean. The latest forecast indicates that the moderate La Ni a conditions are likely to continue at least till the end of winter season,” the IMD said.
The impact of La Nina was visible as 2020 witnessed above normal monsoon with nine per cent excess rainfall this year. The winter season last year had long spells of cold waves.