How does hail form?

This week’s weather question comes from Taylor Hayes of Columbus, Georgia. He wants to know how hail forms.

Hail is produced in thunderstorms. In order for hail to form, you need an updraft and supercooled water molecules.

But what is an updraft? I can demonstrate this with tea bags and a match.

On hot summer days – when we see some of our strongest storms – heat on the surface rises and helps form cumulonimbus clouds – or those dark, towering storm clouds. Heat rises and when there is enough of the heat – it will rise and push up the hail in the clouds – just like how this tea bag rises when there’s the fire (or heat) at the surface.

The clouds with these updrafts extend so high in the atmosphere that the tops of the cloud are actually below freezing – but the water molecules aren’t frozen yet. This is called supercooled water.

Once this supercooled water collides with a dust particle for instance – it freezes on contact instantly. That little piece of ice then continues to grow bigger and bigger the more it runs into supercooled water and freezes on contact. It bounces up and down as it is pushed upward by the updraft until the hail grows so heavy and so large it falls from the sky. And that’s how hail is formed.

If you have your own weather or science related question, send it to Meteorologist Carmen Rose at!

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