UPSC Previous Year Question | Prelims GS | 2019

Why are dewdrops not formed on a cloudy night?

  1. Clouds absorb the radiation released from the Earth's surface.
  2. Clouds reflect back the Earth's radiation.
  3. The Earth's surface would have low temperature on cloudy nights.
  4. Clouds deflect the blowing wind to ground level.

Answer

Correct Answer

Clouds reflect back the Earth's radiation.

Explanation

Dew forms when surfaces cool by radiating heat on clear, calm nights. On cloudy nights clouds reflect/return the Earth's outgoing radiation, so the ground does not cool enough to reach the dew point and dew does not form.

Topics: climatology - condensation, dew formation, geography, physical geography