Mercury set to dip, dense fog likely

Dense fog is likely to prevail in the city on Wednesday, with the minimum temperature also set to dip, according to weather experts.

Dense fog is likely to prevail in the city on Wednesday, with the minimum temperature also set to dip, according to weather experts.

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The city recorded a minimum temperature of 7.7 degrees Celsius and a maximum temperature of 20.9 degrees Celsius on Tuesday, according to the India Meteorological Department’s (IMD) Palam Observatory in Delhi, which, according to the MeT department officials, gives a fairly accurate reading of the city’s weather. The IMD’s automatic weather station (AWS) did not record the city’s minimum temperature on Tuesday.

On Wednesday, the minimum temperature is expected to settle around 4 degrees Celsius, while the maximum temperature may stay around 22 degrees Celsius, as per the IMD’s weekly forecast. IMD officials said that a fall in minimum temperature by 1-3 degrees Celsius might be recorded in some parts of the plains in northwest India and central India during the next three days.

“Cold wave conditions are likely to prevail tomorrow in Delhi-NCR tomorrow in isolated pockets. The sky will remain clear while moderate to dense fog might prevail in the morning hours. The maximum and minimum temperature might settle around 24 and 4 degrees respectively,” said an IMD official.

Air quality in the city deteriorated and entered the very poor category on Tuesday, with a reading of 377 on the Central Pollution Control Board’s (CPCB) air quality index (AQI) bulletin. This was up from Monday’s reading of 271, which put the city in the poor category. Experts attributed the deterioration in air quality to the accumulation of airborne pollutants, on account of poor wind speed.

However, Gurugram was the least polluted city in the National Capital Region (NCR) on Tuesday, as the AQI in the neighbouring Delhi, Noida, and Ghaziabad spiked to the severe categories on Tuesday.

The level of ultrafine particulate matter having a diameter of 2.5 microns or less (PM 2.5), the city’s primary pollutant, was 270.38 micrograms per cubic metre (µg/m³) on Tuesday, as per the CPCB’s air quality monitor at Vikas Sadan in Sector 11.

According to the early air quality warning system for Delhi-NCR, the air quality is likely to improve marginally but remain in severe to the very poor category on Wednesday. The air quality is likely to remain in the very poor category on Thursday as well.

Subsequently, air quality is expected to stay in the very poor category over the next five days since surface winds are likely to remain light, due to which ventilation will be poor. “Due to low wind speed and thermal inversion, the air pollutants are not being dispersed. The mixing height is also at the lowest right now,” said Sachin Panwar, a city-based independent air quality scientist.

Panwar said that the wind direction is expected to change around December 25, which would aid the dispersal of pollutants.