A moon with a 22 degree halo.

There’s an old weather saying that a ring around the moon means rain soon. There’s some truth to this saying;  halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads. and these often precede bad weather. Sure enough, it has been raining very large cats and enormous dogs all morning
Cirrus clouds contain millions of tiny ice crystals. The halos are caused by both refraction and reflection of light within the ice crystals.