I was home in my backyard at night, I can only see them at night and only when there are clouds. I always look up whenever I'm outside so when I saw these lights, on top of a giant cloud, it caught my eye. I had no idea what it was when I saw this light show, but I thought it was very strange.I see groups of lights, hard to tell how many, but at least 4. They move around quickly and seem to each have their owna pattern, as if each one goes a different route but all traveling the same pattern.I live in Las Vegas so at night I can always see the beaming light from the Luxor, however I cannot see a source for these cloud lights. I have gone looking in my car and tried to find a source for these lights, and since Vegas is relatively small, I could not find any source on the ground that would explain why there are lights above the clouds.I first noticed these lights maybe a year or so ago. I saw them many nights on top of the clouds, then they just stopped for a few months and they have started up again.I lost sight of them when the clouds move.Also, I'm sure you'll think I'm crazy, but the clouds have all kinds of faces on them. I had my daughter look at them sometimes to see what she thought it looked like and she saw the same thing as I didI think I've covered all your criteria but if you'd like anymore info, I will do my best to get it for you.Any ideas what this could be?