Let’s talk about hail

Simone Abelli, meteorologist at Centro Epson Meteo, answered MeteoHeroes’s  questions about hail.

How and when does hail form?

Hail forms during thunderstorms, in cumulonimbus clouds which are very high clouds due to the energy involved. Hail forms in the part of the cloud where temperature are below zero.

How big can a hailstone get?

Hailstone dimension can vary and it dipends on the energy triggered by the thunderstorm: if there’s a lot of energy, the vertical draft (a small‐scale current of rising air within a cloud)  is more intense and it keeps the hailstones up in the air. This way hailstone have the time to grow in size, moving up and down in the cloud.
Only when hailstones are too heavy for the vertical draft, they fall down on Earth.

When, during the year, is more common to see hailsones?

Without a doubt hail is more common during the summertime, a little less common during autumn or spring. During the cold season thunderstorms can still form, but mainly by the sea: this happens when colder air moves in higher layers of the atmosphere above the warmer sea. This triggers the energy needed for thunderstorms to form.

grandinata