Why does the moon sometimes have a huge circle cloud around it sometimes ?

I have seen this twice know lots of other people have seen it I am sure .I am curious to know why does the full moon create an cloud effect that make a circle that expands for many miles.It lstrange thier are clouds every where but right where the moon its like a perfect circled shaped cloud that is in a form of a circle.what does metorlogist call this?Why does the moon sometimes have a huge circle cloud around it sometimes ?
That's the moon light refracting on ice crystals, means is likely gonna snow in your area soon. It's called a halo.Why does the moon sometimes have a huge circle cloud around it sometimes ?
Toxic Moontrails:



http://www.chemtrailcentral.com/Why does the moon sometimes have a huge circle cloud around it sometimes ?
its a moon bow cause by light being refracted by ice crystals in the sky
i dont know what it is either! i saw it like the night before and my mom tried to take a picture of it but failed. i noticed that it was directly over the town. it looks very beautiful also. you should look it up