Trends in Air <span title="Pressure......Question/////help?">Pressure......Question///...</span>

Question

1.) What causes air pressure?

2.) Why does air pressure decrease as you go up in altitude?

3.) When preparing for a climb, many climbers will measure the air pressure at the highest altitudes to which they will be climbing. Why do they do this?

Answer 1

Altitude, pressure on molecules.  

As you get higher there is less air being forced down. Like if you were tackled and you are on the bottom of the pile. You will have more weight on you then the guys on top.

Less air pressure means less available oxygen. Because the air is less dense it will take more breaths to obtain oxygen the body needs. Your body will need to adjust as the ascend in altitude.