Definition of Hail

Hail refers to a form of solid precipitation distinguished by ice formations, named hailstones, that are either spherical or irregularly lumped. These hailstones originate in strong thunderstorms, specifically those characterized by intense updrafts and supercooled water droplets. The size spectrum of hailstones is broad, from small pellets akin to peas to large balls measuring several inches across.

Formation of Hailstones

Hailstones develop through an intricate procedure within the confines of a thunderstorm:
1. Updrafts and supercooled water droplets: Robust updrafts in a thunderstorm lift raindrops into the storm's frigid upper regions. As they elevate, the raindrops meet supercooled water droplets that, despite being under the freezing temperature, continue to exist in liquid form.

2. Hailstone growth: The collision between supercooled water droplets and raindrops results in the freezing of the former onto the latter, creating an initial hailstone. As the thunderstorm's updrafts and downdrafts circulate the hailstone, it has the opportunity to collide with more supercooled water droplets, which contributes to its enlargement.

3. Hailstone fall: Once the hailstone's weight exceeds the updrafts' lifting capability, it falls towards the ground, manifesting as hail.

Hail Size and Damage Potential

Hailstones carry the potential to cause considerable harm to property, agriculture, and vehicles. The size of a hailstone is proportional to the strength of a thunderstorm's updrafts, with powerful updrafts capable of keeping hailstones airborne for longer periods, thereby enabling their growth. The National Weather Service utilizes specific size references to denote hailstones:

- Size commensurate with a pea (0.25 inches)
- Size similar to a quarter (1 inch)
- Diameter corresponding to a golf ball (1.75 inches)
- Size comparable to a tennis ball (2.5 inches)
- Diameter equivalent to a baseball (2.75 inches)
- Size approximating a softball (4 inches)

Hail Climatology

Regions with a high occurrence of thunderstorms, notably the central United States or "Hail Alley," experience frequent hail incidents. Certain locales in Europe, Asia, and Australia also exhibit recurring hail events. Hailstorms commonly occur during warmer months, a time that coincides with an increased likelihood of thunderstorms.

Hail Detection and Forecasting

Meteorologists utilize radar and satellite data to detect and track thunderstorms capable of producing hail. Doppler radar is particularly effective in identifying strong updrafts and hail within a storm. In predicting the occurrence of hailstorms, forecasters use computer models in conjunction with an understanding of atmospheric conditions.
Updated: Jun 2, 2023
Published by: Weather Atlas | About Us