What does a thicker layer on a hailstone indicate?

A thicker layer on a hailstone indicates that it has spent more time in the upper regions of the cloud. In the formation of hailstones, they are successively lifted and dropped within the cloud due to updrafts and downdrafts. The longer a hailstone remains in the colder parts of the cloud, the more layers of supercooled water droplets it can accumulate, leading to a thicker outer layer as it experiences repeated cycles of freezing and melting.

This process occurs in storms that have strong updrafts, which sustain the hailstone in the cloud long enough for significant layers to form. The thicker the hailstone, the more time it has spent growing in the cloud, rather than being rapidly ejected or falling prematurely. Other choices may describe different aspects of hail formation but do not specifically address the duration of time spent in the cloud as directly as the chosen answer does.