Why may dew formation be less likely on a cloudy night?

Correct answer: Clouds reduce radiational heat loss from the ground

Correct answer: B. Dew normally forms when a surface cools to the dew point and water vapour changes into liquid droplets. On a clear night, the surface loses heat efficiently by radiation. Clouds act like a partial insulating blanket: they absorb some outgoing terrestrial radiation and re-radiate energy back toward the surface. This reduces the rate at which the ground cools, so the surface may not reach the dew point. A is not a physical atmospheric process. C is the opposite of the usual effect; clouds generally moderate surface cooling rather than making every surface colder. D is incorrect because clouds do not simply remove all condensation nuclei, and nuclei are not the main reason given for the reduced likelihood of dew here. Dew can still form on a cloudy night if the surface becomes sufficiently cool and moist, so “less likely” is more accurate than “impossible.” Memory cue: clouds cover the sky and cover the ground from rapid radiational cooling.