The weather gods came to Delhi’s rescue the day after Diwali, helping the city take a breather from the incessant cookie popping on Saturday. While Delhi’s air quality index remained in the ‘severe’ zone on Sunday, high wind speeds and rain in various parts of the city helped improve the air. This improvement is expected to continue through Monday, when AQI levels are likely to return to the ‘very poor’ zone, according to the weather forecast.
Senior scientists from the Indian Meteorological Department (IMD) said that a western disturbance, which began affecting the western Himalayas on Saturday, brought widespread and moderate rains to Delhi NCR. Delhi recorded 0.4mm of rain as of 5.30pm (at Safdarjung Observatory) on Sunday and the average wind speed over the city reached 40km / h in the afternoon.
Kuldeep Srivastava, head of IMD’s regional weather forecast center, said the direction of the wind blowing over Delhi shifted from northwest to east, which also reduced the transport of stubble smoke from Punjab and Haryana.
“At the Safdarjung Observatory, the maximum temperature was recorded at 29.1 degrees Celsius, while the minimum temperature was 11.4 degrees Celsius, two degrees below normal for the season. Wind speeds will remain high in Delhi and NCR overnight on Sunday, helping to disperse pollutants, ”said Srivastava.
IMD recordings show that the Palam observatory recorded 1.8mm of rain, Ridge recorded 1.2mm of rain and in Jafarpur and Najafgarh, 1mm of precipitation was recorded as of 6.30pm on Sunday.
Unlike in previous years, when air pollution levels are still very high, moving to “severe” category the day after Diwali, this time air pollution levels were gradually reduced the day after Diwali due to favorable weather conditions.
For example, in 2019, Diwali was on October 27. The Air Quality Index (AQI) on October 27 and 28 was 337 and 368 respectively, both in the “very poor” category. But on October 29-30, air quality deteriorated to the category of “severe” with an AQI of 400 and 419.
“Delhi this time escaped from prolonged exposure to severe air pollution due to Western unrest. It has brought rains and showers to many parts of Northwest India. Wind speed began to increase from Sunday morning, registering more than 10 km / h, causing a gradual dispersal. The winds were strongest at night when it started to rain. We expect air pollution levels to drop significantly tonight, ”said Vijay Soni, a scientist in IMD’s air quality division.
The ventilation index on Sunday was approx. 10,000 m2 / s. The ventilation index is a function of the mixing height and the wind speed and defines the capacity of the atmosphere to disperse pollutants. A ventilation rate of less than 2,350 square meters / second is considered poor.
Mixing height is the height at which the pollutants in the air mix.
The winter cold is likely to set in in northwestern India in a couple of days due to the impact of the WD. “The minimum temperature is likely to drop by 2-4 degrees C in the next few days due to cold winds from the Himalayan region,” said M Mohapatra, IMD CEO.
The western unrest swept through Afghanistan and the neighborhood on Sunday. Under the influence of western disturbance, an induced cyclonic circulation and its interaction with lower-level easterly winds, widespread rains accompanied by thunderstorms, hailstorms and lightning were recorded in the western Himalayan region.
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