Delhi woke up to a foggy morning with nil visibility and obscured sky. Most parts of NCR witnessed similar conditions, dull and gloomy, restricting free flow of traffic, particularly the aviation sector. Palam airport reported zero visibility between 7.30am and 8.30am, also reducing the runway visual range (RVR) to 100mtr. Patchy dense fog on earlier occasions at the airport lasted for short duration and without dropping RVR, least impacting the aviation.
Very dense fog obscuring both, horizontal and vertical visibility was practically missing this season, has made a late start. Month of December passed conspicuously scot-free, possibly 1st time in the last many years. Also, the total number of thick fog hours declined well below the average values. The poor record blame can be apportioned to low frequency of active western disturbances over the Indian region. Inactive weather system across the mountains also delayed the snowfall, getting rolled over to January.
Dense fog formation is facilitated by set of meteorological conditions. Low temperature in the range of 5-8°C, high relative humidity (>90%) and Nil/light wind supports dense fog through a deep layer of atmosphere. This morning, minimum temperature stayed between 6-7°C, dry and wet bulb temperature remained same resulting 100% humidity and nil wind conditions prevailed through the night and early morning. An ideal combination of meteorological parameters broke the jinx of uninterrupted good visibility conditions, so far. More of it is expected and might even repeat tomorrow.
National capital has not observed any cold wave days during January 2022, so far. Earlier, in December 2021, base station Safdarjung registered 4 of these, when the minimum temperature plunged to </= 4°C. Yes, cold day conditions have been observed for couple of days, when the day maximum temperature hovered around 15°C, during 1st half of Jan 22. Similar trend looks like in the coming 7-10 days. Day maximum temperature is likely to stay close to 16°C today as well. Minimum temperature is not expected to breach 4°C mark and therefore still evade cold wave conditions. However, meteorological conditions appear to be favorable for recurrence of dense fog over the weekend.