Gases are compressible fluids. When under higher pressure, gas is compressed. All of the molecules are pushed closer together, creating a higher concentration. When you lower the pressure, the molecules are allowed to seperate some, lowering the concentration. Increasing your altitude lowers the atmospheric pressure, which allows the oxygen in the air to spread out some, lowering the concentration.

danetp

January 30, 2009

i am going to have to disagree with you russztt, maybe i am wrong here, but just because you increase in altitude (decrease atm pressure) doesnt mean there is necessarily less oxygen concentration does it? let me know

RussZTT

January 08, 2009

"That doesn't matter, forced induction systems get rid of altitude issues" Incorrect. Even top fuel dragsters run slower. Forced induction cars still pull air from the higher altitude that has less oxygen.