Iridescent Clouds Near Orsta, Norway

Provided by: Geir T. Øye
Summary authors & editors: Geir T. Øye, Jim Foster 

The photo above shows a striking example of cloud iridescence that was visible over Ørsta, Norway on the afternoon of February 11, 2006. Iridescence in clouds is caused by diffraction of sunlight. Iridescent clouds can be thought of as detached coronae in that they're visible only in the vicinity of the Sun. The metallic colors that are the hallmarks of these typically mid-level clouds result when cloud droplets deflect or interfere with sunlight or moonlight.