Originally Posted by DodgeRida67
Vacuum means nothing... pressure means nothing... all they do is define a pressure differential. What you are looking for is atmospheric pressure differential. It's all about the pressure differentials.
why atmospheric? that would be storms and stuff. Just because you're talking about pressure relative to atmospheric pressure doesn't make it "atmospheric pressure differential".
but you're right, of course, pressure differential is like a source of potential energy. It's much the same as voltage or height (in fact height causes a dP). In fact, pressure and voltage are very analogous (think of water in a pipe and current in a circuit: V=P, I=flow, R=proportional to drag etc..)