Why must rising air reach the dew point before cloud formation?

Correct answer: Because at that temperature air becomes saturated and condensation begins

Answer: A. The dew point is the temperature to which air must be cooled, at its existing moisture content and pressure, for it to become saturated. As air rises, it expands and cools. Before reaching the dew point, the air is unsaturated, so there is not yet a necessary condition for widespread condensation. At the dew point, relative humidity reaches about 100 percent; further cooling allows water vapour to condense on suitable particles, forming cloud droplets or ice crystals. A is correct because it gives the actual sequence: rising, cooling, saturation, and condensation. B is wrong because air still contains water vapour at the dew point. C is wrong because dew point is an atmospheric moisture-temperature measure, not ocean depth. D is wrong because cloud formation requires saturation, not merely warmth. Memory cue: dew point means “cool enough to condense.”