The national capital was enveloped in a thick layer of fog on Monday morning, with the visibility reducing to zero at the Palam weather station. This was the season’s first heavy fog, said officials of the India Meteorological Department (IMD). It also contributed to the deterioration in Delhi’s air quality, which almost touched the “severe” mark.
According to IMD officials, ‘there was “very dense fog” at Palam, disrupting flight operations and road traffic during the early hours of Monday.
RK Jenamani, head of the Indira Gandhi International (IGI) airport’s MeT department said, “For around three hours—between 6.30am and 9am—the visibility was zero. It was only after 9am that it improved to 50 metres here. When visibility is zero, flight operations have to be suspended. The runway visibility was 75-125 metres. There was a sudden change in atmospheric conditions because of easterly winds that resulted in a thick fog cover. We expect ‘dense’ to ‘very dense’ fog on Tuesday as well; however, the intensity will be on the lower side.”
At the Safdarjung Observatory, representative of Delhi’s weather, “moderate” fog was observed with the visibility reduced to 300 metres at 8.30am. “The season of fog has started. Easterly winds that were blowing over Delhi till Sunday noon brought moisture. High moisture content combined with low wind speed resulted in heavy fog. On Tuesday, we are expecting ‘dense’ fog at Safdarjung while ‘very dense fog’ at Palam,” said Kuldeep Srivastava, head of IMD’s regional weather forecasting centre.
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He added that at Safdarjung, the visibility may reduce to less than 200 metres on Tuesday morning. Also, air quality is likely to remain in the higher end of “very poor” because of the impact of fog, which makes the air heavier allowing higher concentration of pollutants. “Though moisture content will start reducing from Tuesday, its impact will be felt only later in the day. Also, wind speed will pick up to 10-12kmph, which may result in an improvement in air quality on December 9-10,” said Srivastava.
Also, Delhi may see “very light rain” or drizzle on December 11 on account of a western disturbance that will affect the whole of northwest India, including Delhi. “Till at least December 12, there will be no significant change in the morning and night temperatures. Only after the passing of the WD, there could be a drop in temperature,” he said.
On Monday, the minimum temperature was 12 degrees Celsius, three notches above normal. The maximum settled at 26.3 degrees Celsius, two notches above normal.
As per the Central Pollution Control Board (CPCB), the average air quality index (AQI) reading was 400, in the “very poor” zone, just one notch away from “severe” (401). It was 389 on Sunday. On Saturday, Delhi’s air quality was in the “severe” zone with an AQI reading of 404.
At least 12 of the 35 monitoring stations, including those in major hot spots, already recording air quality which breached the “severe” category. On a scale of 0-500, an AQI value between 301-400 is considered “very poor” while 401-500 is “severe”.