November rain highest in 12 years in Delhi — did little to help pollution

Despite the higher-than-usual rainfall brought by western disturbances and spread over four rainy days, Delhi’s air quality remained polluted all through the month, with the average AQI for November being the second highest from 2017 onwards.

Meanwhile, the city’s AQI on Saturday was 353, in the ‘very poor’ category, marginally better than 372 on Friday, according to the Central Pollution Control Board (CPCB).

Delhi also saw its first ‘dense’ fog episode of the winter so far on Saturday, when the lowest visibility recorded at the IGI Airport was 50 m. Dense fog persisted from 6.30 am to 9.30 am at Palam, according to an official in the IMD. This resulted in the diversion of 20 flights that were headed to Delhi to Jaipur, Lucknow, Ahmedabad, Amritsar and Chandigarh between 7.30 and 10.30 am.

Fog forms at low temperatures when water vapour condenses. According to the IMD, a cyclonic circulation lies over the northeastern Arabian Sea along with a trough from this cyclonic circulation to northeastern Madhya Pradesh.

Under the influence of these systems, dense fog is likely in parts of Punjab, Haryana, Uttar Pradesh, and north Rajasthan on Sunday as well.

In Delhi, moderate to dense fog is expected from Sunday to Tuesday, going by the forecast. Fog is categorised as ‘dense’ when visibility is 199 m to 50 m.

The minimum temperature, which was 12.3 degrees Celsius on Saturday, is likely to remain at around 11 or 12 degrees over the next three days.