Delhi witnesses moderate fog, very poor air: IMD

Air quality is likely to remain in the lower end of the “very poor” category on January 18 and 19 according to air quality warning system for Delhi

There was moderate fog with visibility of less than 500 metres in many parts of Delhi on Monday morning. The minimum temperature at 5.30am at Safdarjung was 11 degrees Celsius.

Commuters on a foot overbridge amid dense fog in New Delhi. (Amal KS/HT PHOTO)

Delhi’s air quality was recorded in “very poor” category with air quality index (AQI) of 376.

Air quality is likely to remain in the lower end of the “very poor” category on January 18 and 19 according to air quality warning system for Delhi under ministry of earth sciences.

Currently, easterly winds are prevalent at lower levels over plains of north India. This is likely to cause a gradual rise in minimum temperatures by 2-4 degrees Celsius over most parts of northwest India during the next 48 hours (till 19 January). Thereafter, reversal of wind direction to westerly/northwesterly is likely from January 20. This will lead to a gradual fall in minimum temperatures by 2-4 degrees Celsius during subsequent 2-3 days (January 20 to 22) over the same region. An approaching western disturbance is likely to impact the western Himalayan region on January 22 which is likely to cause widespread snowfall in the hills.

“Cold day” to “severe cold day” conditions in isolated pockets are likely over Punjab, Haryana, Chandigarh and Delhi during the next 24 hours and “cold day” conditions in isolated pockets over Uttar Pradesh, Bihar and West Bengal during the next two days.

According to IMD, a cold day or a severe cold day is classified as such based on two parameters—a minimum temperature of under 10 degrees Celsius and maximum temperature of 4.5 degrees Celsius or 6.4 degrees Celsius below normal, respectively.

A cold wave occurs in the plains when the minimum temperature is 10 degrees Celsius or below and/or is 4.5 notches lower than the season’s normal for two consecutive days. A cold wave is also declared when the minimum temperature is less than 4 degrees Celsius in the plains.