we called it a “snow ring”. the bigger the ring, the better the chance for snow. This shot is being added to my collection. THank you so much since I am now in the south and do so miss walking in the snow like my family did today in the philly area.
It is an optical phenomena based on a layer of ice crystal cloud in the upper atmosphere.
The angle of the ring(s) are always the same. The brightest and most common, as I recall, is a 22 degree halo, the next is the 46 degree halo. There are only the two.
They apply to both the sun and the moon.
Depending on the angles, all partial rings can be seen. They are often known as "sun dogs", seen as bright spots on both sides of the sun.