What is the primary dynamic cause of cyclonic rainfall in the atmosphere?

Correct answer: Meeting of two air masses with contrasting temperatures and densities

Correct answer: B. Cyclonic or frontal rainfall is associated with a low-pressure system and the meeting of air masses having different temperatures and densities. At a front, the denser cold air tends to remain below while the warmer, lighter air is lifted over it. As the rising air expands, it cools; when it reaches the dew point, water vapour condenses into clouds and precipitation may follow. The central idea is forced uplift caused by the interaction of contrasting air masses and the circulation of a cyclone. A may heat air and produce convection, but it is not the defining dynamic cause of cyclonic rainfall. C describes relief or orographic rainfall, where mountains force air upward. D contributes moisture locally but does not create the frontal lifting mechanism. Memory cue: cyclonic rain is linked with “fronts and forced ascent,” whereas mountain rain is orographic.