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Hail

✨ The Sky's Ice Cubes

Hail is a form of solid precipitation made up of balls or irregular lumps of ice called hailstones. It forms inside powerful thunderstorm clouds, known as cumulonimbus clouds, where strong upward air currents repeatedly lift water droplets high into very cold parts of the cloud. There, the droplets freeze and grow as new layers of supercooled water freeze around them.

This cycle may happen several times before the hailstones become too heavy for the rising air to support. They then fall to the ground, sometimes together with heavy rain, strong winds and lightning. Hailstones vary greatly in size, from only a few millimeters across to several centimeters during the most intense storms.

Unlike snow, which develops as ice crystals, hail forms through repeated freezing inside thunderstorm clouds. It can occur in many parts of the world, especially during warm seasons when the atmosphere is unstable enough to produce powerful storms. Large hailstones may damage crops, roofs, windows and vehicles, while also posing a risk to people and animals caught outdoors.

Weather radars help meteorologists detect hail-producing storms and issue warnings before they reach populated areas. Although hailstorms usually last only a short time, they can cause significant local damage. Studying how hail forms also helps scientists better understand severe thunderstorms and improve weather forecasting.

💡 Did you know?

Did you know that hailstones hide a memory inside? If you cut a large one in half, you'll see circular layers, a bit like an onion! Each layer corresponds to a journey of the ice cube up and down in the cloud. Opaque circles are made of ice frozen quickly with air bubbles, and clear circles of ice frozen more slowly.

The largest hailstone ever recorded weighed nearly 1 kilogram! That's as heavy as a carton of milk. It fell in Vivian, South Dakota, in 2010. It measured about 20 centimeters wide, which is huge! When hailstones of this size fall, they can reach speeds over 160 km/h and cause major damage to cars and roofs.

Did you know that to form a large hailstone, you need incredibly powerful air currents? The winds inside the storm must blow upward at over 100 km/h to keep the ice cube in the air as it grows. Without these vertical winds, the ice cube would immediately fall as light rain. It's a real battle between gravity and the wind!