So what’s an “arcus cloud?”

They can look like something out of a movie, an alien invasion on the horizon, but the bizarre shape in the sky is an arcus cloud.

Arcus cloud is the umbrella term for a low, horizontal cloud formation that usually accompany’s thunderstorms. You may know them as shelf clouds and roll clouds.

>>RELATED: What's the difference between a shelf cloud and a wall cloud?

We see both types of these arcus clouds in the Miami Valley. In northeast Ohio this week, a complex of thunderstorms produced some impressive shelf cloud photos.

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