The pressure above (or below) atmospheric is a gage pressure. Represents positive difference between measured pressure and existing atmospheric pressure.
The pressure above (or below) atmospheric. Represents positive difference between measured pressure and existing atmospheric pressure. Can be converted to absolute by adding actual atmospheric pressure value.
the pressure relative to atmospheric pressure. Gage pressure = absolute pressure minus one atmosphere.
Pressure measured with respect to atmospheric pressure.
The pressure measured relative to the local atmospheric pressure. Gage pressure may be negative. A negative gage pressure is known as suction or vacuum.