Look at the moon now in San Jose, Ca.
What causes the ring around the moon. The sky is cloudy. With the Moon in the center of a circle of perfectly clear sky.
If you are just talking about a circular gap in the clouds with the moon in the middle, I would guess its just a coincidence, but you may be seeing a halo.
I think you have got what I was looking at. The sky around the moon in an almost perfect circle was clear. I have seen this before but tonight it was such a large circle. It was something to see. Thanks.