around 2000 My sister and I lived in Golden, Colorado and were at home watching over her son. After he had gone to sleep we went out on the porch of our condo for a cigarette . Rain is not uncommon at this time of year so having large clouds looming close to the mountains did not alarm us. However. Within minutes the clouds took on a dark green colour (the kind one would see ahead of tornadoes) and began slowly stretching upward creating a very very tall wall of rolling green cloud. We expected heavy rain and got none. As we watched (did not have camera available or cell phones at that time) the center of the cloud got very wispy and out glides one of these big balls you see on overhead wires and lines to keep airplanes clear of them. (random picture attached) it was brightly coloured and close enough that we could see that they were solid just like the spheres on wires and each was a different color. As it slowly floated across the sky we noticed that the green cloud was so big and tall it was blotting out quite a bit of sky between the mountain and us. And then several more of these spheres glided out of the clouds wispy center at different speeds and different heights . None changed speed while in motion but the fast ones traveled fast the entire time we could see them and the slow ones just poked along . The glide of these spheres was effortless, silent, and totally horizontal. We watched them until they flew too far away to see anymore. Around twenty total came from the cloud at staggered intervals and glided in plain sight until out of view. We told almost no one because the few we told had the expected reaction. Felt like this was the only place i could get it out and not be laughed out of a job or friendship.