Graupel Facts for Kids

A handful of graupel pellets

Graupel is a type of frozen water that falls from the sky. It looks a bit like tiny, soft hail or small snow pellets. You might find it falling during cold weather, often mixed with rain or snow. Unlike hail, which is hard and icy, graupel is soft and crumbles easily when you touch it. It's different from regular snow because of how it forms and its texture.

What is Graupel?
- How Does Graupel Form?
- What Does Graupel Look Like?
Graupel vs. Snow and Hail
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What is Graupel?

Graupel is a form of precipitation, which means it's any kind of water that falls from clouds to the Earth's surface. It's often called "soft hail" or "snow pellets." Graupel forms when tiny, supercooled water droplets freeze onto a falling snowflake. These water droplets are colder than freezing point but still liquid. When they hit the snowflake, they instantly freeze, making the snowflake grow into a small, round, icy pellet.

How Does Graupel Form?

Graupel forms in clouds where the temperature is around or below freezing. Here's how it happens:

Snowflakes start falling: First, regular snowflakes begin to fall from the upper parts of a cloud.
Supercooled water: As the snowflakes fall, they pass through a layer of the cloud that contains tiny water droplets. These droplets are "supercooled," meaning they are liquid even though their temperature is below freezing (0°C or 32°F).
Freezing on impact: When a snowflake hits these supercooled water droplets, the droplets instantly freeze onto the snowflake. This process is called "riming."
Growing into pellets: As more and more supercooled droplets freeze onto the snowflake, it becomes heavier and more rounded. It loses its original snowflake shape and turns into a soft, opaque pellet of graupel.

What Does Graupel Look Like?

Graupel pellets are usually small, often less than 5 millimeters (about 0.2 inches) across. They are typically white and opaque, meaning you can't see through them. Because they are soft, they often bounce or break apart when they hit the ground. This is different from hail, which is much harder and usually bounces without breaking.

Graupel vs. Snow and Hail

It's easy to confuse graupel with snow or hail, but there are key differences:

Snow: Snowflakes keep their delicate, crystal shapes. They are light and fluffy. Graupel, on the other hand, is more like a tiny, rounded ball of ice that has lost its crystal shape due to riming.
Hail: Hail forms in strong thunderstorms. It's made of layers of ice, like an onion, and can be very hard and large. Hailstones can cause damage. Graupel is much softer and smaller, and it usually falls during lighter winter weather, not severe storms. It doesn't cause damage like hail.

Graupel often falls during "wintry mix" conditions, which means a mix of rain, snow, and freezing rain. It's a common sight in many cold regions around the world.