Wx Savvy | Winter

Sleet and Hail Are Different!

Sleet and hail are both pieces of ice, so how are they different?

The way sleet forms is very different from how hail forms. Sleet forms during the winter while hail occurs mostly in the summer during thunderstorms.

Sleet- Sleet is much smaller than hail and often called ice pellets. Sleet is a frozen raindrop. It forms when a raindrop or a melted snow flake freezes before hitting the ground. This occurs when it is above freezing high up in the clouds and below freezing at or near the surface. Or the water starts as a snowflake, but as it falls it hits a layer of above freezing temperatures and melts. As it falls farther it encounters below freezing air near the surface and re-freezes into an ice pellet or sleet.

(Hail split in half shows rings)

Hail- Hail usually forms in thunderstorms which have strong updrafts and downdrafts. The hail gets caught up in these strong up and down winds that often reach 100 mph. While going up and down, then up again and down, then up and so on...the small frozen particle will encounter super cooled water droplets which freeze onto the hail. This is how hail grows so big as it builds frozen layer after frozen layer. This layering is unique to hail and why when split in half you can see what looks like tree rings in the hail. Eventually the hail will become to heavy for the updraft and fall to earth.

By the way, the terms that describe hail like "golf ball sized" and "pea sized" are actually approved National Weather Service descriptors.

(Large hail)

Did you know? Super cooled water droplets are water drops that despite being in below freezing air, remain liquid. They can exist as a liquid as cold as -40°F. The super cooled water droplet remains liquid until it finds something to freeze onto. As soon as the super cooled water droplet comes into contact with, for example, a piece of hail, it will freeze making the hail even bigger. Super cooled water droplets are what make up freezing rain. They freeze on contact with the ground, trees, power lines, anything at all.