Hail is actually responsible for some big monetary loss disasters in the country.
All too often during severe weather season, hail takes a back seat to tornadoes but many storms are notable just because of the gigantic hail they throw out. These big ice chunks from thunderstorms form and fall to the ground with intense fury.
Hail is usually pretty irregular in size as its birth is quite violent up inside of thunderstorms. To get hail formation, you need strong, upward motion of air within a storm — meaning you need lots of instability and wind shear for the biggest hailstones. A lower freezing level also will contribute to big hailstones.
Severe hail is considered any hail over 1″ in diameter, or quarter size or larger.
How Hail Forms
Hail begins as droplets of water — as these droplets rise and the temperature falls below freezing hailstones begin forming as the supercooled droplets interact with condensation nuceli. Because of this, hail tends to form in layers, like an onion.
Storm updrafts can have wind speeds of over 100mph going straight up, which can help keep hailstones lofted for a long time, letting them grow into gigantic sizes such as baseball, softball, or grapefruit size.
Hail will rise in a thunderstorm until its mass becomes too great for the thunderstorm to keep lofted. It is at that point that hail will fall back to earth.
What Ingredients Favor Hail Growth
Hail is more common in places like the Great Plains — where evaporational cooling can lower the freezing level of thunderstorm clouds. This gives hail a larger amount of space to grow big.
Typically, the higher the instability and wind shear — the greater hail growth potential is — but its not that simple. There are other factors such as the freezing level height which can impact the possible hail maximum size on any given chase day.