Because if it is produced by humans to power environment destroying SUVs it will never ever condense and fall from the sky.
Gotcha.
We better get ManBearPig on this one before the planet is melted.
My point is that, even though we’re in a closed system and won’t be “creating” new water vapor you look over LA with the traffic it will be almost a constant fog and we’ll really hear how the hydrogen fuel cell was another bad idea.