Geography question from JKAS Prelims, 2018 by JKPSC
Which of the following atmospheric conditions is most favourable for the formation of fog in Delhi?
Last updated Jun 13, 2026
Correct Answer:
Option D —
Clear sky, humid air in winter
The type of fog that commonly forms in Delhi during the winter months is Radiation Fog. For radiation fog to develop, specific meteorological conditions must align:
Clear Sky: A clear sky at night allows the Earth's surface to rapidly lose heat accumulated during the day through longwave terrestrial radiation. If the sky is overcast, clouds act as a blanket, trapping the heat and preventing the surface from cooling down sufficiently.
Humid Air: High relative humidity means the air contains a substantial amount of moisture. As the ground cools rapidly under a clear sky, it cools the adjacent layer of air. If there is enough humidity, the air temperature drops to its dew point, causing the water vapor to condense into tiny liquid water droplets (fog).
Winter Season: Winter provides the long nights necessary for prolonged radiational cooling to take place, lowering temperatures enough to trigger condensation.
Calm Winds: Though not mentioned in the options, light or calm winds are also crucial. Strong winds would mix the cold surface air with warmer air above, preventing the fog from forming.
Answer verified by Quintessence Classes faculty — Karan Nagar, Srinagar.
