Lenticular clouds (altocumulus lenticularis) are sky phenomena often interpreted like UFO presences. These particular clouds can be generally seen on the top of the mountains, where different wind streams merge.
If temperature permits it, the steam creates enormous conglomerates similar to lenses. These clouds are a real danger for pilots because of the turbulence areas.
Lenticular clouds are the object of many legends going from UFO to gods’ kingdom.