Light rain was seen across the city because of a western disturbance on Thursday afternoon, even as the average air quality dipped from the ‘very poor’ category a day before into the ‘severe’ category (AQI of 429). The maximum temperature in the city dipped to 19.8 degrees Celsius, five degrees below normal. The minimum, however, was four degrees above normal at 13.4 degrees Celsius owing to a dense cloud cover overnight. Partly cloudy skies are expected in the city on Friday, with the temperature expected to be between 22 and 12 degrees Celsius. The turn in weather was caused by a western disturbance. Another western disturbance is expected to bring rain on Monday. Officials said that because of the dip in temperature as well as humidity, shallow to moderate fog is expected on Friday and Saturday morning, as well as Tuesday and Wednesday. “As forecast, Delhi experienced poor visibility throughout the day with very light rainfall on Thursday afternoon. Palam airport station reported a visibility of 700-800m in shallow fog/smog till 10 am. It then improved to 1200 m till 1 pm but dipped again to 500-800 m in mist/ light rainfall till the evening. Safdarjung too saw a similar trend. While the minimum temperature was well below normal, it could not be technically declared as a cold day as the criteria for the minimum temperature to be under 10 degrees Celsius was not fulfilled,” said a senior IMD official. The maximum temperature is expected to be between 22 degrees and 24 degrees Celsius over the coming seven days. Because of the cloud cover, the minimum temperatures are expected to be around 12-13 degrees Celsius. The air quality, meanwhile, turned severe primarily because of weather conditions and internal pollution sources. Officials at SAFAR said that low temperature and calm winds were the primary reason behind the deterioration. “For the next three days, winds are likely to be calm, reducing ventilation and leading to deterioration of air quality. From December 6, winds are expected to increase dispersing pollutants but AQI is likely to remain in the ‘very poor’ category. Partly cloudy sky and low mixing layer height are preventing efficient dispersion of pollutants,” the SAFAR forecast said.
