Editing Altostratus cloud (section)

== Optical phenomena ==
Altostratus clouds can produce bright [[Halo (optical phenomenon)|halos]] when viewed from the air,<ref name="WMO-Desc">{{cite web|url=https://cloudatlas.wmo.int/en/observation-of-clouds-from-aircraft-descriptions-altostratus.html|title=Altostratus|access-date=25 March 2022|publisher=World Meteorological Organization|website=International Cloud Atlas}}</ref> but not when viewed from the ground.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.6.2}}</ref> Halos can take the appearance of rings, arcs, or spots of white or multicolored light and are formed by the [[Reflection (optics)|reflection]] and [[refraction]] of sunlight or moonlight shining through ice crystals in the cloud.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 3.2.3.1}}</ref> Light diffraction through altostratus clouds can also produce [[Corona (optical phenomenon)|coronas]], which are small, concentric pastel-colored rings of light around the sun or moon. They can also be [[Iridescence|iridescent]], with often-parallel bands of bright color projected on a cloud. Unlike the halos, the coronas and iridescence can be seen from Earth's surface.<ref name="MetOffice" /><ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 3.2.3.2 &ndash; 3.2.3.3}}</ref>