Atmospheric optical phenomena in which the Sun appears to have risen
This article is about the phenomenon of later dawn and is not to be confused with the earlierFalse dawn.
A "false sunrise" (in the form of a fragmentary upperSun pillar) as seen nearBologna,Italy in October 2008. Note the "lake-reflection" effect which is not real because there is no water in between.
Afalse sunrise is any of severalatmosphericoptical phenomena in which theSun appears to haverisen, 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 thesunlight 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 resemble that of the 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 ofice crystal halo, such as anupper tangent arc or, more commonly, an uppersun pillar (similar to asubsun, but extending above the sun instead of below it). Like allhalos, these phenomena are caused by the reflection and/or refraction of sunlight byice crystals suspended in the atmosphere, often in the form ofcirrus orcirrostratus clouds. 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 ofmirage, specifically theNovaya Zemlya effect. Restricted mainly to the polar regions, this phenomenon was named after its first observation onNovaya Zemlya during the third polar expedition led byWillem Barentsz in 1596/97, when the Sun was seen above the horizon "in his full roundness"[1] two weeks before its predicted return after thepolar night. The account, written by officerGerrit de Veer, was met with general skepticism for centuries, and not until modern times was the effect proven to be genuine.[2]
The term "false sunrise" should not be confused with "false dawn", which is a term sometimes used to refer to thezodiacal light.
^Siebren van der Werf,Het Nova Zembla verschijnsel. Geschiedenis van een luchtspiegeling ("The Novaya Zemlya phenomenon. History of a mirage"), 2011;ISBN978 90 6554 0850.
