Season’s worst fog envelopes Delhi; trains, flights delayed

A northern railways spokesperson said the Puri-New Delhi Purushottam Express and the Howrah-New Delhi Poorvah Express were running late by over five hours

At least 25 trains and around 50 flights were delayed as the season’s worst fog enveloped Delhi in the early hours of Wednesday and plunged visibility to 50 metres in Safdarjung and Palam even as the air quality was likely to deteriorate to the severe zone again later in the day.

The fog on Wednesday was the thickest across north India. (HT PHOTO)

A northern railways spokesperson said the 25 trains were delayed by more than an hour. The Puri-New Delhi Purushottam Express and the Howrah-New Delhi Poorvah Express were running late by over five hours. “...in winters during dense fog, trains are run at reduced speeds to avoid any mishaps.”

No flight diversions were reported until 9am even as around 50 flights were delayed. A flight is classified as delayed when it is late by over 15 minutes.

An India Metrological Department (IMD) official said the fog on Wednesday was the thickest as it intensified across north India. “It developed in the night and morning hours and has lasted a longer duration as compared to Tuesday,” said the official. The visibility plunged to 50 metres in Amritsar at 6pm on Tuesday. It dropped to 50 metres in Lucknow and Agra by 11:30pm. “In Delhi, Safdarjung and Palam have 50-metre visibility. It dropped to 150 metres at Palam at 4:30am and to 50 metres by 7am,” the official said.

The IMD classifies fog as shallow when visibility is between 500 and 1000 metres, moderate when it is between 200 and 500 metres, dense when it is between 50 and 200 metres, and very dense when it is 50 metres or lower.

Delhi recorded an average Air Quality Index (AQI) of 380 (very poor) at 9am on Wednesday, compared to 377 (very poor) at 4pm a day earlier while the mercury dipped to 7°C.

The air quality was likely to deteriorate and remain in the severe category until Friday. It was likely to be between very poor and severe zones for the subsequent six days.

The AQI improved on Monday after remaining in the severe zone for three days but stayed much over safe limits.

The mercury was expected to go up to 22°C. Delhi recorded a maximum temperature of 23.8°C on Monday and 24°C on Tuesday. Experts have attributed the warmer day-time temperatures to the El Nino weather phenomenon.