What is a simple difference between frost and snowfall?

Correct answer: Frost forms on surfaces while snowfall falls from clouds

Correct answer: A. Frost and snowfall both involve ice, but their location and formation process are different. Frost forms directly on a cold surface when water vapour deposits as ice crystals, or when moisture freezes on that surface under freezing conditions. It is therefore a surface deposit. Snowfall, in contrast, consists of ice crystals or snowflakes that form in clouds and fall through the atmosphere to the ground. A correctly distinguishes formation on the surface from falling from clouds. B is wrong because frost can form on many exposed land surfaces, not always in the sea. C is wrong because snowfall is associated with clouds and atmospheric conditions, not with stones releasing snow. D is wrong because the two phenomena have different origins and movements. A useful caution is that frost is not simply snow lying on the ground; it forms in place. Memory cue: frost stays where it forms, while snow falls from above.