This astounding image captured above the mountains of Montana looks like the first sign of an alien invasion.
In fact, it is a lenticular cloud, which often forms in a UFO-like saucer shape, triggering reports of extraterrestrial sightings.
The apocalyptic sky appeared over the jagged peaks of the Crazy Mountains just as the new year began.
It comes just weeks after such clouds were spotted in a more unlikely setting, above Fatsley in West Yorkshire.
The spectacular vision is created when moisture droplets are pushed up a steep slope, condensing into cloud on their way and warming up to return to water vapour as they move down the other side.
These clouds are known as Altocunulus lenticularis - referring to their lens-shape - and hover high in the air, usually over the Andes, Himalayas or the Rockies.
This terrifyingly beautiful sight appeared as high winds blew over the mountains on New Year's Day.
Bright colours are sometimes seen along the edge of lenticular clouds, which are said to be the single biggest explanation for UFO sightings across the world.
The awe-inspiring formations have also been known to appear in cases where a mountain does not exist, as the result of shear winds created by a front.
Read more: http://www.dailymail.co.uk/news/article-2082443/Apocalypse-cloud-Extraordinary-sight-appears-Montanas-Crazy-Mountains-New-Years-Day.html#ixzz1jYXnsusB
