Delhi’s air quality improves, temperature falls

According to IMD, the minimum temperature at the Safdarjung observatory, which is considered the official recording for Delhi, was 8.4°C and the maximum temperature was 19.4°C.

While the national capital’s temperature fell, with the India Meteorological Department (IMD) officially announcing the onset of winter, strong winds that blew over Delhi from Sunday night helped improve its air quality from “very poor” to “moderate”.

People warm themselves next to a bonfire on a cold winter evening, at Minto Road, in New Delhi on Monday. (Raj K Raj/HT PHOTO)

Despite Monday being a sunny day, the minimum and maximum temperatures fell in Delhi. According to IMD, the minimum temperature at the Safdarjung observatory, which is considered the official recording for Delhi, was 8.4°C and the maximum temperature was 19.4°C, which was four degrees below the season’s normal.

On Sunday, Delhi recorded a maximum of 20.7°C—three notches below normal. The minimum, meanwhile, was recorded 11.1°C.

Scientists said that cold northwesterly winds from Himachal Pradesh, Uttarakhand and Jammu and Kashmir, which are experiencing heavy snowfall, are the reason for the fall in Delhi’s temperature.

“Even though the sky is clear and it is sunny, the cold winds are not allowing the ground to get warm and this is the reason we are feeling colder,” Kuldeep Srivastava, the head of IMD’s regional weather forecasting centre, said.

Meanwhile, the Central Pollution Control Board data shows that the overall air quality index (AQI) reading of Delhi on Monday was 160, in the “moderate” range, which is uncommon for the month of December when the low temperature and wind speed lead to high pollution.

In many pollution monitoring stations, such as the ones in Aya Nagar, Lodhi Road, Pusa, and Indira Gandhi International Airport, the average hourly AQI readings had reached the “satisfactory” zone.

On Sunday, the overall AQI reading was recorded 305, in the “very poor” zone. IMD scientists said that strong winds which continued to blow over Delhi from Sunday evening helped dispersal of pollution particles.

Srivastava said, “After the passing of a western disturbance, which took place on Saturday, wind speeds tend to pick up and that’s what Delhi experienced. On Sunday night, winds picked up and continued to blow through the night, which is rare because, during winters, wind at night tends to be calm. On Monday too, the winds were consistent and the average speed was around 12-15kmph.”

Srivastava said that the wind speed is expected to improve further on Tuesday, which will keep the pollution levels low.

VK Soni, head of IMD’s environment monitoring research centre, also said that air quality over the next few days is expected to remain in the “moderate” to “poor” range. “We do not see any major deterioration at least for the next three or four days,” he said.