Ask A Met: What's The Difference Between Hail And Snow?

This week's question comes from Morning Brief reader Ted, who asks, "What's the difference between hail and snow?"

Meteorologist Jonathan Belles: The easiest answer is that hail bounces. It's bouncy.

But we shouldn’t just be talking about the difference between hail and snow, because sleet, which is somewhere between hail and snow, also bounces. Everything from rain to snow is on the same spectrum.

Fun fact: Almost every cloud in the sky, except for maybe in the deep tropics, has snow in it.

The way you get from rain to hail on that spectrum is a process called convection. You're used to it in thunderstorms; you're used to it in your microwave.

Basically, heat makes things go up, and every cloud, whether it be in the tropics or elsewhere, has these nuclei, usually made of water but sometimes they can be ash or pollution or dust, and they tend to grow.

When these nuclei with water or snow get pushed up and down, they tend to freeze a couple of times on the way up or down. Most particles start off as snow and they melt on the way down.

If the particle travels within a thunderstorm that is tens of thousands of feet tall, particularly in the summer when the air at the bottom of the atmosphere creates more convection, you eventually form a stone that is cold enough and heavy enough to fall to the ground still frozen.

Rain doesn’t bounce and snow doesn’t bounce. But hail and sleet bounce when they hit the ground. Hail can be round or spikey and, as we know, can be as small as peas or as large as a softball.

Sleet is like Dippin’ Dots, because they’re small but not quite 100% spherical.

The next step on that spectrum would be when we get to snow. That happens when the atmosphere is completely cold all the way up and down. Without heat in the lower atmosphere, the particle doesn't have a chance to melt between the cloud and the ground.

Without the process of reshaping that forms hail and sleet, snow comes down more directly. Snowflakes, particularly wet snow, are usually a little bit heavier. They tend to come straight down.

It is possible to have hail, sleet and snow together, though.

In the Plains, for example, you can have a thunderstorm that's riding on that front edge of the cold air. In front of that storm, it'll be 80 degrees and behind it, it'll be 30 degrees. With that kind of massive temperature difference, you get both the warmer process to make hail and, on the backside, all hell will be breaking loose in a snowstorm in the same storm system.

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