dark frosty, of all the arguments against the ARK story, your's is the one that hold no water, because
*sigh*, here we go again...
Like the rising tide that lifts all boats, the air would have been merely lifted up, and with a new sea level still be at it's maximum at that new lowest possible altitude, quite warm too with all that energy of motion.
Yes, it would have been lifted, but not at the same density, because...
mass now BELOW the ark would have increased the surface gravity, and with it the pressure and the temperature at the new sea level.
Actually, the opposite would happen. The large large large majority of gravitational pull from earth comes from the denser rocks, metals, mantle, etc., not water. Adding 8800+ meters of LESS dense material will actually decrease the overall strength of the gravitational field over the given surface, not decrease it. It's the same reason Saturn, with much more mass than Earth, has about the same gravitional pull at the surface. It's all about density.
Pushing the atmosphere that high while weakening the surface gravity would have allow massive amounts of the atmosphere to bleed off into space, lightening the atmosphere and making it much colder still that it previously would have been.