Question: why does the presure of gas get more as you get higher up a mountain?

Jon Benton answered on 19 Mar 2012:

As you go up a mountain the pressure actually decreases – the air becomes thinner and it becomes harder to breathe. The reason for this decrease is that atmospheric pressure is the measurement of force acting downwards. Therefore the higher you climb the less atmosphere there is above you so there is less pushing down on you resulting in a lower pressure.