what causes hail to form

Hail forms inside powerful thunderstorms when strong updrafts keep ice particles circulating high in a very cold part of the cloud, allowing them to grow into balls of ice before finally falling to the ground.

Quick Scoop: What Causes Hail to Form?

The basic recipe for hail

Think of hail as rain that got repeatedly “re-frozen and bulked up” inside a storm.

Key ingredients:

• Moisture: Plenty of water droplets in the storm cloud to freeze.

• Unstable air: Warm, moist air near the ground and much colder air higher up, which helps storms grow tall.

• Strong updrafts: Powerful rising air inside a thunderstorm that can lift raindrops very high, above the freezing level.

• Cold temperatures aloft: A deep layer of air below 0°C in the upper cloud where droplets and pellets can freeze.

Step‑by‑step: How a hailstone grows

1. A small “seed” forms, often a frozen raindrop or graupel (a soft ice pellet) high in a cumulonimbus cloud.

2. Strong updrafts carry this seed into very cold regions filled with supercooled water droplets (liquid water below 0°C). These droplets instantly freeze on contact, adding a new layer of ice.

3. The growing hailstone becomes heavier, starts to fall, then may be caught again by the updraft and lifted back up. Each cycle through supercooled droplets adds more layers, like an onion.

4. When the hailstone becomes too heavy for the updraft to support, or the storm weakens, it falls to the ground as hail.

If you cut a large hailstone open, you often see these layered rings of clear and cloudy ice, showing each growth cycle inside the cloud.

Why some storms make giant hail

• Stronger, more sustained updrafts can keep hailstones suspended longer, so they grow larger before falling.

• Wind shear (winds changing speed and direction with height) helps organize and tilt storms, separating updrafts from downdrafts so hailstones don’t fall out too quickly.

• Very cold upper-level air plus abundant moisture provide lots of supercooled droplets to freeze onto the hailstone.

This is why the same thunderstorm type that can produce tornadoes and damaging winds often also produces large hail.

Why hail doesn’t always reach the ground

• Small hailstones can melt on the way down if the air near the surface is warm, so you might only see heavy rain or slushy ice pellets.

• When hailstones are large enough, they fall fast and retain their solid ice all the way to the ground, causing damage to crops, cars, and roofs.

A quick example image in your mind

Imagine a busy elevator in a skyscraper:

• Updrafts are the elevator , carrying droplets and ice up to the freezing floors.
• Gravity is the down direction, pulling them back toward the lobby.
• Each trip up and down, the “passenger” (the hailstone) picks up another coat of ice until it’s too “heavy” for the elevator to lift—and then it crashes out of the building as hail.

TL;DR: Hail forms when strong thunderstorm updrafts repeatedly lift ice particles through supercooled water high in a cold cloud, building up layers of ice until the stones are heavy enough to fall to the ground.

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