DOH! I just posted my version but tradivoro's version is much better with his cool texture he found! So I deleted it. :)

My only other contribution that I had that would apply to T's method is to use a boolean difference to clip off the top of the cone. If you do that you can better focus the cones light to the breaks in the clouds. Here is a picture I did to show the clipping of how it looks on the sky. :)