When you see a halo around the sun or moon it means a storm is coming A ring or circle of light around the sun or moon is called a halo by scientists. We get many messages throughout each year from people who’ve just spotted a ring around the sun or moon. On May 14, 2013 a solar halo was seen over the U.S. east coast … see photos of May 14 halo here. People want to know: what causes a halo around the sun or moon? Keep reading … answers below. There’s an old weather saying: ring around the moon means rain soon. There’s truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly clear. After all, you can see the sun or moon. And yet halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads.
These clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals. The crystals have to be oriented and positioned just so with respect to your eye, in order for the halo to appear.”