The India Meteorological Division (IMD) has issued an orange alert for “dense” to “very dense” fog in Delhi on Monday, predicting that visibility could drop to as little as 200m in a lot of the Capital and the encircling area, affecting highway, rail, and air visitors.
Thick layer of smog at NH24 close to Akshardham Temple in New Delhi on Sunday. (Arvind Yadav/HT Picture)
“There are chances of dense to very dense fog in Delhi on Monday. An orange alert has thus been issued, with smog expected later in the day too,” mentioned an IMD official.
IMD defines “shallow” fog in a area when visibility drops to 500-1,000m, “moderate” fog when visibility is 200-500m, “dense” fog when visibility is 50-200m, and “very dense” when visibility dips to 50m or decrease.
If visibility is lower than 1,000 metres and relative humidity is greater than 75%, it’s termed as fog. If the relative humidity is lower than 75%, it’s referred to as smog.
All of the runways at Delhi’s Indira Gandhi Worldwide (IGI) are geared up with CAT-3 — an instrument touchdown system (ILS) that permits flights to land in antagonistic climate circumstances reminiscent of fog, even when visibility is all the way down to 50 metres. Nevertheless, flights can not take-offs if the visibility is lower than 125 metres, and so, “dense” or “very dense” fog can result in lengthy delays at IGI.
For instance, Delhi on November 13 recorded the season’s first “very dense” fog, and the flight monitoring web site Flightradar24 mentioned that greater than 550 flights had been delayed that day. Although the bottom visibility was 400 metres the subsequent day, a cascading impact of delays meant over 350 flights had been late — each arrivals and departures.
The Met division mentioned the bottom visibility on Sunday was 500 metres at Palam between 8.30 am and 9 am, whereas it went all the way down to 300 metres at 7 am at Safdarjung. Nevertheless, with the solar’s rays not having the ability to penetrate to the floor, visibility remained poor all through the day, touching a most top of 900 metres at Palam (5.30 pm) and 800 metres at Safdarjung (2.30 pm).
“Visibility did not go beyond 1,000 metres during the day, which is usually when we see some relief through sunshine. In comparison, the highest visibility on Saturday during the day was 2,200 metres. After 6 pm, visibility started dropping again and was at 600 metres at Palam and 400 metres at Safdarjung,” mentioned the official, including {that a} additional dip is probably going after midnight.
As a result of low visibility, trains are more likely to be delayed, whereas pace restrictions are more likely to be applied for highway visitors.
In its forecast for Monday, IMD mentioned, “The fog/smog may affect some airports, highways and railway routes in the areas of Met sub-division. Ferry services also to be affected. Difficult driving conditions with slower journey times.”