(a) Clouds absorb the radiation released from the Earth’s surface.
(b) Clouds reflect back the Earth’s radiation.
(c) The Earth’s surface would have low temperatures on cloudy nights.
(d) Clouds deflect the blowing wind to ground level.
Answer: (b)
Option (b) is correct: Dew is formed when the atmospheric temperature draws the level to the dewpoint temperature. This often happens at ground level for two reasons. First, longwave emission causes the Earth’s surface to cool at night and condensation requires the temperature to decrease to the dew point. Second, the soil often acts as the moisture source for dew. Warm and moist soils will help with the formation of dew as the soil cools overnight. Dewdrops are not formed on a cloudy night because clouds reflect back the Earth’s radiation.
Additional Information: The ideal conditions for its formation are clear sky, calm air, high relative humidity, and cold and long nights. For the formation of dew, it is necessary that the dew point is above the freezing point.
