There are tiny losses from the upper atmosphere, but not enough to matter. If you look at the water cycle[0], you'll see that as the water vapour rises it cond

There are tiny losses from the upper atmosphere, but not enough to matter. If you look at the water cycle[0], you'll see that as the water vapour rises it condenses - it gets quite cold a few miles up. Clouds consist of tiny droplets of liquid water and ice, not vapour. [0] https://en.wikipedia.org/wiki/Water_cycle https://en.wikipedia.org/wiki/Water_cycle