Hailstones are balls or irregular lumps of solid ice that fall from the sky during strong thunderstorms.

Quick Scoop

  • Hailstones form inside tall thunderstorm clouds (cumulonimbus) when powerful updrafts carry raindrops high into very cold parts of the atmosphere, where they freeze into ice.
  • As they are tossed around by rising and falling air, they collect more supercooled water droplets that freeze onto them, so the hailstone grows layer by layer like an onion.
  • When the hailstone becomes too heavy for the updraft to hold up, it falls to the ground as hail.

What hailstones look like

  • Each individual piece of hail is called a hailstone and is usually a round or irregular lump of ice.
  • Many hailstones show layers of clear and cloudy ice in cross‑section, revealing different stages of growth inside the storm.
  • Typical sizes range from about 5 mm up to several centimeters across, but the largest can reach around 15 cm and weigh more than 0.5 kg, which can be very destructive.

Why hailstones matter

  • Any thunderstorm that produces hailstones reaching the ground is called a hailstorm, and stones larger than about 2 cm across are usually large enough to cause damage.
  • Hail can dent cars, shatter windows, strip leaves from trees, and injure people and animals caught outside, which is why weather services issue special warnings when large hail is expected.

In simple terms: hailstones are frozen “ice balls” grown and polished inside a violent storm, then dropped to the ground once the storm can’t hold them up anymore.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.