According to the IMD, very dense fog is when visibility is between 0 and 50 meters. When visibility is between 51 and 200 meters, it is termed dense fog, 201 to 500-meter visibility falls under moderate, and shallow is between 501 and 1,000 meters.
Visibility dropped to zero meters third time this season
This is the third time this season, after December 8 and January 1, that visibility has dropped to zero meters in the city.
Delhi recorded a minimum temperature of 6.6 degree Celsius on Saturday.
The Lodhi Road weather station recorded a minimum temperature of 5.8 degree Celsius.
On Friday, the Safdarjung Observatory had recorded a low of 6.4 degree Celsius.
No improvement in the city's air quality
Meanwhile, there was no improvement in the city's air quality which remained in the severe category on Saturday.
The city's AQI was 436 at 9 am on Saturday. The 24-hour average AQI was 460 on Friday, and 429 on Thursday.
Air Quality Index (AQI) had entered the severe category on Thursday due to extremely unfavorable conditions for the dispersion of pollutants, government agencies said.
Moisture in the air has made the pollutants heavier: IMD
Kuldeep Srivastava, the head of the IMD's regional forecasting center said, "The wind speed has slowed down and the moisture in the air has made the pollutants heavier."
The Central Government's Air Quality Early Warning System for Delhi said, "Slow winds and ventilation conditions are extremely unfavorable for the dispersion of pollutants. This will lead to further deterioration of the air quality."