Alaskans took to social media to document the dark gray column of smoke tunneling over Lazy Mountain. While the unusual formation worried enough of them to report it to Alaska State Troopers on ...

The strange spectacle is formed when "shear winds" blowing past each other roll a cloud into a log of sushi, or a ghostly passenger train, maybe some kind of tunnel through the fourth dimension.

Many people constantly report seeing the strange cloud formation.

This strange cloud formation is the result of both human activity and disturbances in the atmosphere.

Did you see something that looked like bubble clouds with Monday's storms? These unusual formations are known as mammatus clouds.

Called a “horseshoe vortex cloud,” these strange cloud formations are so fleeting that people seldom see them and photos are a matter of pure luck, experts say. Facebook screengrab/Stan Dorroh ...