superincumbent
Lying or resting on something else; overlying.
As the vapour cooled the water would be precipitated, and an ocean would surround the spherical nucleus with a superincumbent atmosphere.
Where it comes from
From Latin superincumbentem, present participle of superincumbere. By surface analysis, super- + incumbent.
Adapted from the Wiktionary entry superincumbent (CC BY-SA 4.0).