A ‘very dense’ blanket of fog covered the Delhi airport for at least four hours on Monday morning, with visibility dropping to less than 50 metres. Even though it was the longest spell of ‘dense’ fog the airport had encountered this season, it had very little effect on flight operations.

The India Meteorological Department has warned that moderate to dense fog would continue over the next three days. There is also possibility of rain over the weekend.

“There is a possibility of dense fog on Tuesday and Thursday. On Wednesday, there could be moderate fog. There is high moisture content in the air. Other parameters such as low wind speed and dip in temperature are also ideal for fog formation,” said BP Yadav, deputy director general of IMD.

On Monday, visibility at the IMD’s Safdarjung observatory remained below 200 metres till 8:30 am. At Palam, the general visibility remained below 50metres, from around 5:30 am to 9:30am, resulting in very dense fog. The runway visibility remained between 75metres and 150metres during that period.

“It was the longest spell of dense fog at IGI this season. While very dense fog conditions (visibility less than 50m) were recorded from 5:30am to 9:30 am, dense fog conditions (visibility less than 200m) were encountered from 5 am to 10 am,” said an IMD official.

On a scale of 1,000 metres, IMD declares it as a ‘very dense’ fog if visibility drops below 50m. If the visibility is between 50m and 200m, it is considered as dense fog. Visibility range from 200 m-500m is taken as moderate fog.

Though the airport encountered long hours of fog, only a few flights were affected.

“Arrivals and departures continued well. There were no diversions. There were no cancellations because of Delhi’s weather. Weather at other airports was not good and that affected the arrivals,” said a DIAL spokesman.

Sunday’s rain and a favourable wind speed helped to push down pollution levels over the past two days. While the air quality index (AQI) value had touched 407 on Saturday and was hovering in the severe zone, it dropped to 336 on Sunday. On Monday, the AQI was recorded to be 333, which was in the very poor stage.

Government agencies forecast that even though the air could improve marginally on Tuesday it could deteriorate on Wednesday. The air quality is likely to remain in the very poor stage over the next two to three days at least.

The night temperature was recorded to be 7.1 degrees Celsius, which was normal. The maximum temperature was recorded to be 20.1 degrees Celsius, which was one degree above normal.

First Published: Jan 08, 2019 09:00 IST