What Does it Mean When There Is a Ring Around the Moon and What Causes the Halo?

A ring around the moon means rain or snow is coming soon.

The old folk rhyme is accurate, because high clouds typically streak out ahead of a fall or winter storm.

This veil of wispy cirrus clouds, about 20,000 feet up, is mostly ice crystals that act like tiny prisms in the sky.

They refract or bend the light coming from the moon or sun, forming a halo.