The
absolute pressure of the
ambient atmosphere,
varying with weather, altitude, etc.; expressed in millibars (meteorology) or mm Hg or
torr (respiratory physiology); at
sea level, one
atmosphere (atm, 760 mm Hg or torr) is
equivalent to: 14.69595 lb/sq in, 1013.25 millibars, 1013.25 × 106 dynes/cm2, and, in SI units, 101,325 pascals (Pa).
Synonym:
atmospheric pressure.