In order to understand what a hail storm is, you must first know what hail is. Hail is a type of precipitation. Typically hail falls in little balls of ice like material. Hail balls can be as small as a dime, but sometimes are as large as a softball. Hail storms most commonly come with severe thunderstorms, although they sometimes will accompany a tornado warning. Hail is produced by a type of thundercloud called the cumulonimbi. These clouds are usually seen at the front of a hail storm and are composed of transparent ice layers. It is in these clouds that hail is formed.
Like other types of precipitation, hail will form inside a cloud when super cooled water drops freeze instantly. A thunderstorm will produce updrafts, which blow hail balls into the upper part of the cloud. This will cause an updraft to fall apart and cause the hail balls to fall back down into the cloud. This cycle continues over and over again, lifting the hail up into the draft and sending it back down again. This can cause the hail to increase in size from it’s average size, to something much larger like the size of a golf ball. In order to create hail, you will not only need the updraft, but also high liquid water content, vertical extent, and large droplets of water.
Hail can form just about anywhere but it is typically found along mountain ranges because the winds force air horizontally upward, which increases updrafts, an important characteristic to creating hail. The countries of India and Bangladesh are most commonly known for having the worst hail storms in the world. They report more deaths from hail than any other country in the world. China also reports frequent and severe hail. In the United States, hail is most commonly expected in a region known as “hail alley” which includes Colorado, Nebraska, and Wyoming, with Cheyenne Wyoming being the most hail prone city in the US, at nine to ten hail storms a year.
Hail storms cause a lot of serious damage each year. In fact, hail causes nearly $600 million dollars in damage a year! The most commonly damaged items include cars, airplanes, skylights, and crops. If a person is caught out in a storm, they may even suffer from a concussion or even fatal head trauma, so it is advised to seek indoor shelter away from windows during these storms.