However, if water is present at the base of the column of air, that water partially evaporates (becomes water vapor) and contributes to the atmospheric pressure.
(water; is; present at the base of the column of air) (that water; evaporates; ) (that water; becomes; water vapor) (that water; contributes; to the atmospheric pressure)
water that water that water that water
is evaporates becomes contributes
present at the base of the column of air
water vapor
to the atmospheric pressure