Which characteristic of hail is correct when considering it as an in-flight hazard?

Hail is typically produced during the mature stage of a thunderstorm’s lifespan due to the strong updrafts that are present. During this stage, the towering cumulonimbus clouds have developed into a fully formed thunderstorm, capable of producing severe weather, including hail. The formation of hail involves the repeated lifting of small water droplets by these strong updrafts, which freeze and accumulate layers of ice as they are carried up and down within the storm. Eventually, the hailstones become heavy enough to overcome the updrafts and fall to the ground, creating a significant hazard for aircraft in flight.

In contrast, hail can occur in various conditions and is not restricted to summer thunderstorms alone, nor is it solely small in size — many hailstones can reach large sizes and cause substantial damage. While hail can accompany frontal systems, it is not primarily associated with them, as the phenomenon is more directly linked to the dynamics of thunderstorms rather than frontal activity. Thus, the accurate characteristic highlighting hail as an in-flight hazard is its typical production during the mature stage of a thunderstorm.