SHAFAQNA (Shia International News Association) — ometimes you look up on a clear day or night and see a huge circle of light around the sun or moon. This ring or circle 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. Solar and lunar haloes are pretty common, but they’re so mysterious-looking that people often express amazement upon seeing them.
Notice in the photos that the sky looks fairly clear. After all, you can see the sun. And yet halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads.
Sun halo on May 16, 2012 via EarthSky Facebook friend Nonya Justagirl
These clouds contain millions of tiny ice crystals. The halos you see are glints of light from these ice crystals, which have to be oriented and positioned just so with respect to your eye, in order for the halo to appear.
Sun halo seen in Washington state on May 16, 2012. Image via EarthSky Facebook friend Jana Kitty Daze.
That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own particular halo, made by their own particular ice crystals, which are different from the ice crystals making the halo of the person standing next to you.
Lunar halo via master sky photographer Dan Bush.
Because moonlight isn’t very bright, lunar halos are mostly colorless, but you might notice more red on the inside and more blue on the outside of the halo. These colors are more noticeable in halos around the sun. If you do see a halo around the moon or sun, notice that the inner edge is sharp, while the outer edge is more diffuse. Also, notice that the sky surrounding the halo is darker than the rest of the sky.
By the way, 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.—www.shafaqna.com/english