Volutus, a long cloud which looks almost like a tube spinning in a wave-like motion, was only formally recognized as a cloud for the first time by the International Cloud Atlas earlier this year.
On Saturday it made an appearance in the skies above southern Sweden.
The International Cloud Atlas describes it as “a long, typically low, horizontal, detached, tube-shaped cloud mass, often appearing to roll slowly about a horizontal axis. The roll cloud, volutus, is a soliton, not attached to other clouds and is an example of an undular bore”.
READ ALSO: Crazy UFO cloud spotted by skiers in Sweden
Several cloud fans commented on public broadcaster SVT's Facebook weather page.
“Cool! Clouds are awesome and beautiful,” wrote one. “Apocalyptic,” wrote another.
It's not the first time incredible clouds are spotted in Sweden. This story about a crazy UFO-shaped cloud seen in a ski resort is even one of The Local's most-read articles so far this year.