From pea-sized pellets to record-breaking softballs — every hail size with real-world comparisons, damage descriptions and the storm that spat it out.
In the US, the National Weather Service defines hail as "severe" once it reaches 1 inch in diameter — quarter size. That's the trigger for a Severe Thunderstorm Warning. Under 1 inch, it's still hail, but not officially severe.
Some countries use different thresholds. In Europe, the TORRO hail scale runs from H0 (harmless) to H10 (super-hailstorm) and factors in damage more than diameter.
Hail forms when supercooled water droplets freeze onto a nucleus inside a thunderstorm's updraft. The stone falls, picks up more water, gets lofted back up by the updraft, freezes again, and repeats. Every trip through the freezing zone adds another layer of ice.
A stone the size of a softball needs an updraft over 100 mph to stay aloft long enough to grow — which is why giant hail only happens in the strongest supercells. Related: supercell simulator.