For dew formation, the surface temperature should be near what?

Correct answer: The dew point

Direct answer: B, the dew point. The dew point is the temperature at which air becomes saturated with water vapour when it is cooled, assuming the amount of moisture remains the same. During a clear, calm night, a surface can lose heat and cool toward this temperature. Once the surface reaches the dew point, water vapour near it can condense into liquid droplets, producing dew. B is correct because dew formation depends on cooling to the dew-point temperature or close to it. A is wrong because the Sun’s temperature is unrelated to the local temperature needed for dew. C is wrong because volcanic heat is not a condition for ordinary dew formation and would generally warm the surface. D is wrong because ocean depth is a physical distance, not a temperature. Do not confuse dew point with the freezing point: dew point concerns saturation and condensation, while freezing concerns water becoming ice. Memory cue: dew point is the temperature at which vapour begins to appear as dew.