How does hail grow to the size of golf balls and even grapefruit? The science behind this destructive weather phenomenon

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Brian Tang, University at Albany, State University of New York

(THE CONVERSATION) Hail the size of grapefruit shattered car windows in Johnson City, Texas. In June, 2024, a storm chaser found a hailstone almost as big as a pineapple. Even larger hailstones have been documented in South Dakota, Kansas and Nebraska. Hail has damaged airplanes and even crashed through the roofs of houses.

How do hailstones get so large, and are hailstorms getting worse?

As an atmospheric scientist, I study and teach about extreme weather and its risks. Here’s how hail forms, how hailstorms may be changing, and some tips for staying safe.

How does hail get so big?

Hail begins as tiny crystals of ice that are swept into a thunderstorm’s updraft. As these ice embryos collide with supercooled water – liquid water that has a temperature below freezing – the water freezes around each embryo, causing the embryo to grow.

Supercooled water freezes at different rates, depending on the temperature of the hailstone surface, leaving layers of clear or cloudy ice as the hailstone moves around inside...