If lower air is cold and upper air has ice crystals why does snowfall reaching the ground become more likely?

Correct answer: Because ice crystals can avoid melting

Direct answer: A. Snowfall reaches the ground when ice particles remain solid during their descent. Ice crystals form in cold cloud regions, but they may melt if they pass through a sufficiently warm layer near or below the cloud. In this situation, the lower air is cold, so the crystals are less likely to encounter temperatures high enough for melting. They can therefore remain as snow or join together into snowflakes and reach the surface. A is correct because it identifies the key role of the cold lower layer. B is wrong because cold air does not destroy water vapour; it can hold less vapour and may support condensation or deposition. C is wrong because ice crystals do not become rock. D is wrong because cold air can permit solid precipitation rather than stopping precipitation. Memory cue: cold air below the cloud protects falling ice; a warm layer can turn it into rain.