A few days ago, the North Indian region was engulfed in a thick layer of fog. In fact, cities including Jammu, Amritsar, Chandigarh and Ludhiana were seen witnessing foggy conditions. Moreover, even Delhi was observing zero visibility during the night time.
However, the past two days witnessed no fog. Right from Jammu and Kashmir up to the West Uttar region including Rajasthan, Punjab, Haryana and Delhi were witnessing clear-sky conditions. In fact, the visibility has been the best this season during the morning hours.
This phenomenon does not occur very frequently. You’d be wondering as to why are the entire North Indian Plains are observing such a weather. This condition is attributed to the Nocturnal Jet.
Nocturnal Jet is a fast-moving air current in the lower atmosphere during the night time when sky conditions are clear. As the temperature near the ground drops at night, an inversion layer is formed.
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In this layer, the temperature increases with height which is generally seen up to a height of 5000 feet. This enhances the atmospheric stability and thereby strengthens the horizontal flow of the air. These are stable conditions and during this time, there is hardly any vertical motion, which is mainly responsible for some weather activity over the region.
The last two days have seen temperatures rising from 7 degrees at ground level up to about 15 degrees at 5000 feet. Also, the relative humidity has bee decreasing from 70 percent to just about 10 percent.
In fact, the wind speed is also increasing from light of about 10-15 kmph to 40-45 kmph at 5000 feet.
Usually, for the formation of fog, three factors including high humidity, lower temperatures and light winds are important. However, in the time of the Nocturnal Jet phenomenon, winds are strong along with very low humidity levels.
Thus, these factors put together have inhibited the fog formation over North India. There is indication of a slow down in the wind speed in the next 48 hours. The fog or the mist situation may return thereafter to affect weather conditions in the late night or morning hours.
Image Credit: hindustantimes
Please Note: Any information picked from here must be attributed to skymetweather.com
