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Seasonal Science: Thundersnow

3 minutes

(female narrator) Winter is here. Let it snow, let it snow, let it--Wait. Is that thunder?

Seasonal Science brings you "Thundersnow." If you happen to see the flash of lightning and hear thunder during a snowstorm, consider yourself lucky. In the U.S., less than ten storms per year produce what is known as "thundersnow." But what causes this crazy winter phenomenon, and why is it so rare? First, let's start with your average, everyday, not-so-special snowstorm. A typical winter snowstorm forms when warmer air is lifted over colder air. As the warm air rises, the moisture condenses and forms clouds and precipitation, and due to the cold surface temps, snow falls to the ground. But there's a major difference separating ordinary snowstorms from thunder snowstorms, and that is the speed at which that warm air rises. In a thunder snowstorm, upward moving air rises much faster. We're talking meters per second versus an ordinary snowstorm's centimeters per second. This rapid updraft makes precipitation and cloud particles collide. The faster the updraft, the more collisions, and like in a summer thunderstorm, these collisions cause different cloud parts to develop positive or negative charges. Once the difference in charges becomes large enough, lightning discharges to equalize everything. And what happens after lightning?

[thunderclap]

Hello, thundersnow. Sounds simple enough, right? But thundersnow is rare because getting an updraft that fast during winter is difficult. Cold air in winter tends to make things stable. Only the right circumstances can get air to rise quick enough. Thunder snowstorms form when either warm water heats the surface air, which rises, creating a fast updraft, or when strong weather systems cause air already aloft to rise faster than normal. Even when all the factors are in place, hearing the actual thunder is not a given. Because of all the snow created during such storms, the rumble of thunder is muffled enough that it can only be heard within a couple miles of the lightning source. So, if you do happen to witness this crazy weather phenomenon, go ahead and celebrate. Snow cones anyone?

[people cheering]

Accessibility provided by the U.S. Department of Education.

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What is a thundersnow storm? Most snow storms form when warm air moves into an area in the winter and rising warm air condenses to form snow. If the warm air rises very quickly, the condensing moisture collides with existing particles in the cloud causing electrically charged areas. When a cloud has charged areas, lightning can result. The accompanying sound is why scientists call these thundersnow storms.

Media Details

Runtime: 3 minutes

Seasonal Science
Episode 1
3 minutes
Grade Level: 7 - 12
Seasonal Science
Episode 2
3 minutes
Grade Level: 7 - 12
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Episode 3
4 minutes
Grade Level: 7 - 12
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Episode 4
2 minutes
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Episode 5
3 minutes
Grade Level: 7 - 12
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Episode 6
3 minutes
Grade Level: 7 - 12
Seasonal Science
Episode 7
3 minutes
Grade Level: 7 - 12