The force per unit area that the air exerts on any surface in contact with it. Primarily used for articles pertaining to air pressure within a closed environment. ... (12 Dec 1998) ... Found on http://www.encyclo.co.uk/local/20973
(atmospheric pressure) air pressure is the force exerted on a surface by the weight of the air above it. The internationally recognized unit for measuring this pressure is the kilopascal. Found on http://www.encyclo.co.uk/local/22268