A false sunrise is any of several

atmospheric An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

optical phenomena in which the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

appears to have risen, but is actually still some distance below the horizon. A number of different atmospheric conditions can be responsible for this effect, all of which divert the sunlight in such a way as to allow it to reach the observer's eye, thereby giving the impression that the light comes directly from the Sun itself. The spread of light can sometimes be deceivingly similar to a true sun. Several atmospheric phenomena that may alternatively be called a "false sunrise" are: * Simple reflection of the sunlight off the bottom of the clouds. * A type of ice crystal halo, such as an

upper tangent arc Tangent arcs are a type of halo, an atmospheric optical phenomenon, which appears above and below the observed Sun or Moon, tangent to the 22° halo. To produce these arcs, rod-shaped hexagonal ice crystals need to have their long axis alig ...

or, more commonly, an upper

sun pillar A light pillar is an atmospheric optical phenomenon in which a vertical beam of light appears to extend above and/or below a light source. The effect is created by the reflection of light from tiny ice crystals that are suspended in the atmosph ...

(similar to a

subsun A subsun (also spelled sub-sun) is an optical phenomenon that appears as a glowing spot visible within clouds or mist when observed from above. The subsun appears directly below the actual Sun, and is caused by sunlight reflecting off of num ...

, but extending above the sun instead of below it). Like all halos, these phenomena are caused by the reflection and/or refraction of sunlight by ice crystals suspended in the atmosphere, often in the form of

cirrus Cirrus may refer to: Science *Cirrus (biology), any of various thin, thread-like structures on the body of an animal * Cirrus (botany), a tendril *Infrared cirrus, in astronomy, filamentary structures seen in infrared light *Cirrus cloud, a typ ...

cirrostratus cloud Cirrostratus is a high-level, very thin, generally uniform ''stratiform'' genus-type of cloud. It is made out of ice-crystals, which are pieces of frozen water. It is difficult to detect and it can make halos. These are made when the cloud takes ...

s. The temperature on the ground is irrelevant to their occurrence, meaning that halos can be seen throughout the year and in all climates. * A type of mirage, specifically the Novaya Zemlya effect. Restricted mainly to the polar regions, this phenomenon was named after its first observation on

Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ) is an archipelago in northern Russia. It is situated in the Arctic Ocean, in the extreme northeast of Europe, with Cape Flissingsky, on the northern isla ...

during the third polar expedition led by

Willem Barentsz Willem Barentsz (; – 20 June 1597), anglicized as William Barents or Barentz, was a Dutch Republic, Dutch navigator, cartographer, and Arctic explorer. Barentsz went on three expeditions to the far north in search for a Northern Sea Route, N ...

in 1596/97, when the Sun was seen above the horizon "in his full roundnesse" two weeks before its predicted return after the

polar night The polar night is a phenomenon where the nighttime lasts for more than 24 hours that occurs in the northernmost and southernmost regions of Earth. This occurs only inside the polar circles. The opposite phenomenon, the polar day, or midnig ...

. The account, written by officer Gerrit de Veer, was met with general scepticism for centuries, and not until modern times was the effect proven to be genuine.Siebren van der Werf, ''Het Nova Zembla verschijnsel. Geschiedenis van een luchtspiegeling'' ("The Novaya Zemlya phenomenon. History of a mirage"), 2011; . The term "false sunrise" should not be confused with "false dawn", which is a term sometimes used to refer to the zodiacal light.

References

Atmospheric optical phenomena {{optics-stub

See also

References