A technical term for the work done pushing out the atmosphere by a system that
changes its volume.
A car engine's pistons, for example, have to
push out the atmosphere - in effect lifting a column of atmosphere the same diameter as the piston
vertically through a height equal to the stroke of the piston -
every time they move out. This amount of useless work would
equal Patmos x Swept Volume if the process was quasistatic but, since the process is not, must be
greater than this.