It was an overcast Sunday in the Capital with the air quality continuing to remain in the “severe” category for the sixth consecutive day, while the minimum temperature rose by a few notches. Parts of the city received light rain in the evening.
The average 24-hour air quality index (AQI) based on data from 35 monitoring stations was 459 with PM2.5 as the chief pollutant. Other parts of the NCR like Noida, Greater Noida, Ghaziabad and Faridabad were also in the “severe” level, while Gurgaon was in the “very poor” category.
A forecast by the Centre-run System of Air Quality and Weather Forecasting and Research showed that air quality is likely to be “severe” on December 27 as winds are likely to be low reducing ventilation of pollutants.
‘Slight improvement’
“December 28 onwards, a slight improvement in air quality is likely due to relatively high wind speeds and on December 29, a significant improvement is expected due to high easterly winds resulting in strong ventilation of pollutants,” the forecast said.
The minimum temperature in the city also rose to 9.8 degrees Celsius, which is two degrees above normal for this time of the year and the maximum temperature settled at 21.4 degrees Celsius, which is one degree warmer than normal for the season. The rise in temperatures, the Indian Meteorological Department (IMD) said, can be attributed to overcast conditions and a change in the wind directions.
The winds blowing towards Delhi from the east/south-east direction are warmer than the winds blowing from the north. The IMD has forecast light showers in the Capital as well as dense fog in some areas. The city’s forecast for December 27 said “generally cloudy sky with very light rain/drizzle. Shallow to moderate fog in the morning. The maximum and minimum temperatures are likely to be around 22 and 10 degrees Celsius respectively.”
Western disturbance
The IMD attributed the change in weather to the influence of a western disturbance seen as a cyclonic circulation over east Afghanistan and adjoining Pakistan and an induced cyclonic circulation that lies over south-west Rajasthan and neighbourhood at lower tropospheric levels.
“Under the influence of the above systems, light/moderate to fairly widespread rain/snowfall is very likely over western Himalayan region till December 28 and light rain at isolated to scattered places is very likely over Punjab, Haryana, Chandigarh, Delhi and Rajasthan between December 26 and 28.”
It added that there will be no significant change in minimum temperatures over most parts of north-west India in the next three days and a fall by 2-4 degrees Celsius is expected thereafter.
