Ring around the moon – Rainbow around the Moon
- Filed under: Uncategorized
- Date: Sep 12,2008
Halos are caused by the light of the sun or moon passing through a very thin layer of cirruform (ice-crystal) clouds in the upper atmosphere. The ice crystals refract the light of the moon, similar to the way water droplets in the lower atmosphere can refract sunlight to produce a rainbow. Just like a rainbow, strong halos can have bands of color in them, due to slightly different refractive properties of the ice crystals for different colors. Essentially, halos ARE rainbows caused by primary refraction in ice crystals.
Some interesting facts about halos: Halos always occur exactly 22 degrees away from the sun or moon. Occasionally, intense halos can be double halos, just as intense rainbows can be doubled. Intense halos can also produce “moondogs” or “sundogs,” very bright regions on the halo evenly spaced at 90 degree intervals around the halo.