What is the most important dynamic condition for hail formation in a cumulonimbus cloud?

Correct answer: Strong updrafts

Answer: C. Hail forms inside a deep cumulonimbus cloud where strong rising currents can carry ice particles upward. In the cold upper parts, supercooled water droplets freeze onto an ice embryo. Repeated lifting and falling through regions containing supercooled droplets can add successive layers of ice. The stronger and more sustained the updraft, the longer particles can remain suspended and the larger they may become before gravity brings them down. C is correct because strong updrafts provide the necessary support for repeated growth. A is wrong because weak horizontal wind is not the key vertical mechanism. B is wrong because hail generally needs a deep, powerful cloud, not a thin one. D is wrong because completely dry air does not supply the liquid water needed for growth. Memory cue: “Hail needs a powerful elevator—the updraft.”