ENVIR SCI 1A03 January 13, 2014
Atmospheric Pressure and Density
• What is atmospheric pressure?
o Force exerted by air molecules per unit area
o What triggers atmospheric pressure? – air is being pulled down by
earth’s gravitational field.
o 2 locations: up a mountain and down a valley - - which one has a
higher atmospheric pressure? Valley because of the greater
amount of overlying air (the distribution of air molecules is mostly
found in the valley area)
• Ideal Gas Law used to determine atmospheric pressure
o P = pressure (Pa)
o ρ= air density (kg/m3) Temperatu