Above the mesophere, the upper atmosphere has negligible water vapor content. The Earth's atmosphere contains a so-called "cold trap" at
about 75 km, where the temperature drops to about -100 C. This freezes
the rising water vapor out of the atmosphere.
Good thing, too-- it's why we're here. It prevents water vapor from
rising to the top of the atmosphere, photodissociating from solar UV,
and leaving.
In any case, water is a trivial weight fraction of the atmosphere-- the
drag you'd get from scooping atmosphere would far far exceed the
delta-V you'd be able to get out of electrolyzing water.
Re: AAPG on Global Climate Change ... and get from there to water vapor being 95% of all ... Water vapor approaching 4% of the atmosphere... volume and the saturation pressure drops rapidly with temperature... temperature is both easy to observe,... (sci.geo.geology)
Re: ( OT) Global Warming, a primer . . ... In climate models an increase in atmospheric temperature caused by the ... vapor in turn leads to an increase in the greenhouse effect... Thus water vapor acts as a positive feedback to the forcing provided ... gases in the atmosphere.... (rec.radio.shortwave)
