Longest fog spell since 2019-20 enveloped parts of NCR this week

The IMD said the fog began forming across the region from 7pm on Monday and dissipated around 1pm the following day

Fog enveloped parts of the National Capital Region (NCR) for as long as 18 hours, making it the longest such spell across northern plains since the winter of 2019-2020 as the visibility dipped to as low as 50 metres on Tuesday. The India Meteorological Department (IMD) said the fog began forming across the region from 7pm on Monday and dissipated around 1pm the following day.

Extended fog is not uncommon for this time of the year. (Hindustan Times)

Extended fog is not uncommon for this time of the year and it persists until the sun comes out. “In case, the sun does not come out... [it leads to] a combination of both cold wave and cold day conditions with the maximum and minimum [temperatures] staying low,” said IMD scientist RK Jenamani.

In Delhi, Safdarjung and Palam reported the lowest visibility of 50 metres. Low visibility procedures were in place at the Delhi airport for 10 hours from 11pm till around 9am on Tuesday when the visibility dipped below 800 metres.

The visibility in Delhi was around 50 metres between 3:30 and 6:30am on Tuesday. It gradually improved to 100 metres at 7:30am and over 500 metres by 9:30am.

Visibility under 1,000 metres is classified as fog. Shallow fog means when visibility is between 500-1000 metres. Visibility between 200 and 500 metres is considered moderate fog. Dense fog is when visibility is below 200 metres.

Jenamani said the northern plains have been engulfed in dense fog regularly since December 19. A similar spell of sustained dense fog last enveloped the region in the winter of 2019-2020.

“During that spell, dense fog [engulfed the region] each day between December 19, 2019, and January 7, 2020. We are seeing something similar so far...”

He said the fog intensity will reduce slightly as a fresh western disturbance will lead to cloudy skies and moisture. “Clouds generally impact dense fog formation.”

Chandigarh reported the lowest visibility on Tuesday at 25 metres while it was 50 metres in Haryana’s Ambala and Hisar. In Rajasthan’s Ganganagar, visibility dipped to 25 metres, and to 25 metres in Uttar Pradesh’s Bareilly.