False sunrise

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Extremely rare false sunrise as seen near Bologna, Italy in October 2008. Note the lake-reflection effect which is not real because there is no water in between.

A false sunrise or dawn sundog is a very particular kind of parhelion, belonging to the optical phenomenon family of halos.

It is an atmospheric optical phenomenon associated with the reflection or refraction of sunlight by small ice crystals making up cirrus or cirrostratus clouds in the very particular case when the sun is still below the horizon.

The spread light of a false sunrise has less power than that of a real sun, but sometimes is amazingly similar in its visual behavior at distance. It is very similar to a subsun, except that in a false sunrise the sun is below the horizon and the ice crystals are above it.

See also[edit]