Common sight today hints at approaching rain
BATON ROUGE -
You may have viewed this atmospheric phenomena today that looks like a rainbow ring around the sun or moon. These are called Halos, which is a ring or light that forms around the sun or moon as the sun or moon light refracts off ice crystals present in a thin veil of cirrus clouds. The halo is usually seen as a bright, white right although sometimes it can have color.
A 22 degree halo is the most common type of halo observed, and is formed by hexagonal ice crystals with diameters less than 20.5 micrometers. Light undergoes two refractions as it passes through an ice crystal, and the amount of bending that happens is dependant upon the ice crystal's diameter.
A 22 degree halo develops when light enters one side of the ice crystal's column shape and exits through the other side. the refraction of light occurs twice, once when it enters the crystal and again when it exits.
The two refractions bend the light by 22 degrees from its original path toward Earth, producing a ring of light observed at 22 degrees around the sun or moon.
There is an old weather saying that states: "Ring around the moon means rain soon". There is truth to this saying, since high cirrus clouds usually come before a storm or rain. The same could be said about the sun, as it is all about timing. Look up at the moon early tonight and you may see one!