Sun halo behind a sunshine recorder at the Halley Research Station,Antarctica. This optical phenomenon,also known as a 22 degree halo,is caused by light refracted through ice crystals. Most ice crystals are hexagonal (six-sided). When sun light hits a crystal at a particular angle,it is refracted causing a halo with a radius of 22 degrees. Less common are smaller 9 degree haloes,larger haloes of 46 degrees and partially formed haloes that take the form of arcs. Haloes are associated with approaching rain or snow,as the cirrus cloud that produces the ice crystals is indicative of an approaching frontal system | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / British Antarctic Survey |
Taille de l’image : | 4655 px × 3056 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |