Nephomancy is form of divination that involves observing and interpreting the color, shape and position of clouds in the sky. Nephomancy can be categorized under Aeromancy.
Derived from the Greek nephos ('cloud') and manteia ('prophecy')
The Celtic Druids made extensive use of nephomancy, which they called neladoracht. Meanwhile, a Medieval form of aeromancy involved summoning ghosts and specters to project images of future events onto clouds. François de la Tour Blanche wrote that aeromancy was the art of fortune-telling when specters materialize in the air, possibly with the aid of Demons, projecting images of the future onto clouds like a magic lantern.
Nephomancy is usually done on days when cloud conditions are good. Find a nice location to lie down and just relax. Try not to focus on any one cloud but rather allow the clouds to drift across your view. Visions cannot be forced, they will come naturally when the time is right.
Throughout history symbols of political or religious importance have been seen in the clouds. In A.D. 312 when Emperor Constantine was marching against the army of Maxentius at Rome, both he and his entire army saw a shining cross of light amid the clouds. It was said the cross contained the Greek words “By This Conquer”. Later that night, Christ appeared to Constantine in his dreams bearing a cross in his hand ordering Constantine to have a military standard made in the same image. Under this standard his outnumbered army was victorious.
Some of the U.F.O. sightings have in fact turned out to be disk shaped cloud formations.