If you were woke around 2:30 this morning you would have been amazed to see the winter halo, better known to some as a moon ring. The phenomenon that usually appears in conjunction with a full moon. It appears to be a whitish ring, approximately 10 to 20 times the size of the moon, surrounding the moon and centered on it. Sometimes the ring appear with a color spectacular. It is caused by refraction of the light from the full moon in the ice particles floating in the clouds, as opposed to a rainbow, where light refracts in the water vapor that makes up the clouds.
Since this happens most effectively at a certain angle, this ring appears at the bottom of the clouds, and since similar triangles must form between the moon, the refracting surface, and the observation point, the "highlighted" clouds are at approximately the same distance from the moon, creating the image of a ring.
I personally witnessed this spectacular event in 1979 as a teen, and was in awe. While folklore contributes the sighting as a sign of bad weather to come, and in many cases this has been true. We will just have to wait it out and hope for the best.
So how can rings around the moon be a predictor of weather to come? The ice crystals that cover the halo signify high altitude, thin cirrus clouds that normally precede a warm front by one or two days. Typically, a warm front will be associated with a low pressure system which is commonly referred to as a storm.
It is believed that the number of stars within a moon halo indicate the number days before bad weather will arrive. Give it a try the next time you observe a moon halo