Season’s first fog, visibility down to 800m at Safdarjung

New Delhi: A thick layer of fog blanketed the city early Tuesday morning, reducing visibility to 800 metres at Safdarjung, the city's base station. This marked the season's first instance of shallow fog, arriving after a delay of over a week. According to meteorologists, the fog formation was delayed due to high temperatures and wind patterns.
According to India Meteorological Department (IMD), visibility at Safdarjung dropped to 800 metres between 7.30 am and 8 am. The lowest visibility recorded, however, was at Palam, at 1,200 metres by 8.30 am.
IMD classifies fog intensity based on visibility: ‘very dense fog' is defined as visibility under 50 metres, ‘dense fog' as visibility of 50-200 metres, ‘moderate fog' of 200-500 metres, and ‘shallow fog' between 500 and 1,000 metres. While shallow fog generally appears in Delhi by the end of Oct, dense fog is typically seen starting in Dec.
"The season's first shallow fog was recorded on Tuesday morning, lasting for half an hour. It is usually formed from the last week of Oct, but its formation may vary depending on temperature and wind conditions. The last week of this Oct saw both high maximum and minimum temperatures, which were around five to six degrees above normal. However, Nov saw a dip in temperature, by one to two degrees," said RK Jenamani, senior scientist, IMD. He added that shallow fog is expected to form for one to two hours each morning over the next three days.
Last winter, the first shallow fog appeared on Oct 31, reducing visibility to 800 metres at Palam. In 2022, fog was first observed on Oct 12, with visibility at Safdarjung dropping to 600 metres for two hours, while Palam recorded moderate fog at 300 metres on the same day.
"Unlike the peak winter months of Dec, when fog can persist until noon or even all day, the fog in Oct and early Nov typically lasts for about an hour," said a Met official.