Liljequist parhelion

A Liljequist parhelion is a rare halo, an optical phenomenon appearing on the parhelic circle approximately ±150-160° from the sun between a 120° parhelion and the anthelion (opposite to the sun at the antisolar point).

While the sun touches the horizon, a Liljequist parhelion is located approximately 160° from the sun and is about 10° long. As the sun rises up to 30° the phenomenon gradually moves towards 150°, and as the sun reaches over 30° the optical effect vanishes. The parhelia are caused by light rays passing through oriented plate crystals.cite web
url = http://www.ursa.fi/halot/umi/1995/sa495.pdf
title = Sivuaurinko 4-95 | author = Marko Pekkola, Marko Riikonen
language = Finnish (English summary on last page)
publisher = FHON | date = 1995 | accessdate = 2007-04-22] Like the 120° parhelia, the Liljequist parhelia displays a white-bluish colour. This colour is, however, associated with the parhelic circle itself, not the ice crystals causing the Liljequist parhelia.cite web
url = http://www.ursa.fi/halot/umi/1998/sa198.html
title = Sivuaurinko 1/98 | language = Finnish (English summary at bottom of page)
author = Mika Sillanpää | date = 1998-04-13
publisher = FHON | accessdate = 2007-04-22]

The phenomenon was first observed by Gösta Hjalmar Liljequist in 1951 at Maudheim, Antarctica during the Norwegian-British-Swedish Antarctic Expedition in 1949-1952. It was then simulated by Dr. Eberhard Tränkle (1937-1997) and Robert Greenler in 1987 and theoretically explained by Walter Tape in 1994.

References

See also

* Sun dog
* Liljequist subparhelion

External links

* [http://www.meteoros.de/ee13ee18/ee13_1.htm A fish eye photo by Günter Röttler, Hagen, September 1983] Dead link|date=April 2008 featuring a parhelic circle with a 120° parhelion and a Liljequist parhelion.
* [http://www.halo.astronomie.cz/world/vypis.php List of observations] (pick Liljequist parhelia as a halo filter.)