The lazy winter mornings that Delhi was just getting used to after Diwali was lost in smog on Sunday. A day later, the maximum temperature rose to 32.5 degrees Celsius on Monday — a good three notches above normal.

Monday’s maximum, in fact, was only slightly less than that on Diwali, when it was 33 degrees. The temperature is expected to be warm, at around 31 degrees, on Tuesday, too.

While a drizzle made it a little cooler in some South Delhi localities on Monday evening — it drizzled in parts of Hauz Khas, Mathura Road and CR Park, among others — it was but an offshoot of rains in Chandigarh, Himachal Pradesh and nearby areas, says the weatherman. Tuesday is expected to be dry and hot again.

Experts at the India Meteorological Department (IMD) blame the heat on a phenomenon called “subsidence”, in which warm winds, instead of going upwards, sink towards the ground surface, trapping the heat. “There is no wind to drag away the heat but things are going to get better,” IMD director P B Yadav says.

Unlike most of last week, when temperatures were between 15 degrees and 29 degrees, on Sunday, a day after the smog, it rose to 31.1 degrees.

A slight wind on Monday morning may not have helped bring temperatures down but experts say it led to a decrease in the pollution level.

Dr S D Makhijani, director of the Central Pollution Control Board, says the last three days saw high pollution levels due to three factors: low temperatures, mixing height, and calm winds conditions. “Winters lead to a rise in pollution because these factors lead pollutants to stay near the surface,” he says.

... contd.