A classic ARIA (Always Remembered Instructor's Advice) from Jim when teaching us basic met at Cranwell was in response to a cocky stude (later to be Red 4) who challenged him on the theory of adiabatic expansion. "You keep saying in a perfect model this happens and that happens, but it's not really like that is it??" quoth the stude, or words to that effect. Jim peered out of the classroom windown as if something had suddenly caught his attention. "Beautiful cumulus building up this afternoon isn't there...lovely crisp, white edges, extraordinary thing..." he noted. Cue light bulb over stude's head (and mine).