Strange cloud over Barcelona, SpainThis may not be an "UFO", but what was going on, I don´t know.I witnessed a strange cloud, on a cloudless and mild evening.It stayed stationary in the sky for 3 hours. The top section of the cloud would sort of move out, and swirl around slowly clock-wise.Also, It would never seperate from the rest of the cloud, just re-join it at the bottom of the cloud. Sometimes there would seem to be hole in the middle. The cloud was not round, or any other shape. It was over or near any smoke-stacks, or any thing that could have produced this.It was near the port, but not over the water. It was rather low, and there were NO other clouds in the sky.