You and I know that, and most PFers would understand, but I was thinking of the public at large. It's not just any power plant, but one's the burn fossil fuel. Some nuclear plants use cooling towers, and they put out a lot of water vapor. Some fossil plants use cooling towers, and they put out a lot more water vapor than the flue gas. Some local power plants put out brown flue gas, and I've seen brown clouds drifting east from horizon to horizon.