Atmospheric pressure is the force exerted by the weight of the atmosphere of the Earth at ground level. The value quoted is the standard value but will vary, with variations being measured with a barometer.
|1 atmosphere||= 1.01325x105Nm-2|
|= 1.01325 bar|
|= 1.01325x106 dynes cm2|
|= 14.7 lbf in-2|
|= 76 cm mercury|
|= 406.8 in water|
The air pressure decreases as the altitude increases.