“A second spell of dense fog hit the airport around midnight with general visibility falling to below 200 metres and the runway visual range (RVR) to below 800 metres. Such conditions persisted till 10 am on Monday,” R K Jenamani, director-in-charge of the IGI Met department, said. Similar fog conditions have been reported from Punjab, Haryana and parts of Northwest Delhi.

Visibility at the airport here dropped around 1.30 am on the new runway and around 2.30 am on the main runway. “The RVR ranged between 75-350 metres till 5.30 am on Runway 28 and similar Category III conditions persisted on Runway 29 till 9 am,” Jenamani said.

Several passengers were once again troubled after at least 70 flights were delayed. Nineteen had to be rescheduled, a Jet flight to Mumbai was cancelled, and another Indian Airlines flight from Muscat had to be diverted to Jaipur.

“The LVP was implemented at 12.50 am and was terminated at 10.05 am at the airport. At least 113 flights operated during this time, including 75 domestic and 39 international. Depending on runway visibility, at least 48 flights used CAT I, 27 flights operated using CAT II, 29 operated using CAT IIIA, while 9 others operated using CAT IIIB ILS,” an airport official said.

The new runway inaugurated on December 12 last year has not been put to use on several foggy days. “Runway 28 was used for all arrivals and departures from 12.50 am till about 6.30 am on Monday,” an airport official said.

The Met department said dense fog will affect the airport till January 31. “While humidity is high, the temperature is still very low. These are perfect conditions for fog formation in the presence of calm winds,” Jenamani said.

“We are expecting another spell of dense fog from 5-9 am on Tuesday, as the humidity is still very high at 90 per cent,” he said.

Conditions favourable for fog formation
High humidity: Moisture content in Delhi is very high at 90 per cent. The 4 mm of rainfall on Sunday morning was caused due to the passing of Western disturbances, which increased moisture. Urban meteorology and local availability of moisture keeps humidity levels high.

Low temperature: The Mercury levels have been high and rose above the normal these past few days. The minimum temperature recorded on Monday was 12.9 degrees Celsius, about six degrees above the normal minimum temperature at this point of the season.