Hail forms inside thunderstorms, where powerful updrafts carry raindrops high into freezing air. The drops freeze, fall a little, get caught in the updraft again, and add another layer of ice. Repeat that cycle enough times and you get a stone the size of a golf ball falling at highway speed.

For a farmer, hail is the most sudden kind of loss. A wheat field that looked perfect at noon can be flattened by evening. Vines lose their fruit, maize stalks snap, and young vegetables are shredded. In a few minutes, a whole season's work is gone.

Where it hits hardest

• The North American Great Plains and Canadian Prairies
• Northern India and Bangladesh before the monsoon
• Parts of central and southern Europe in early summer
• High-altitude valleys in the Andes and East Africa

Hail nets over orchards and vineyards are common in vulnerable regions, though they are expensive. Most growers rely on crop insurance, radar warnings, and, in a few places, cloud seeding to reduce the risk.