15 Cases of Bizarre and Mysterious Weather

Clouds don’t really strike fear into the hearts of… anyone. But imagine you were in prehistoric times (or at least pre-History Channel), and giant, swirling masses suddenly appeared in the sky that seemed to be reaching down like huge ghostly fingers. You’d be one freaked out cave-man.

But while your primitive mind might imagine some massive sky-giant was trying to kill you, what you were probably witnessing were Mammatus clouds. These towering cumulonimbus clouds have often been associated with severe storms or tornadoes, but in reality are no more dangerous than your average rain cloud.

via 15 Cases of Bizarre and Mysterious Weather.