The thermal environment of the terrestrial planets /supplement 4/

An atmosphere of Mercury of a light gas such as hydrogen would hardly seem possible.However, since a hydrogen atmosphere is cold, its dissipation o c c u r s slowly, and the l o s s of hydrogen can be compensated by the interception of s o l a r protons.The amount of water in Venus' atmosphere above i t s cloudThe uncerl a y e r is equivalent to a layer of liquid water 98 P deep.tainty amounts to -+ 5%.