Force Applied Over Area
Pressure is defined as force applied perpendicular to the surface of an object per unit area.
Weather and Atmospherics
- Atmosphere (atm): 1 atm represents the mean sea-level atmospheric pressure on Earth.
- Millibar (mbar) / Hectopascal (hPa): Meteorologists universally use these interchangeable units to measure barometric air pressure.
- Millimeters of Mercury (mmHg): Used in medicine to measure blood pressure. Equivalent to the Torr.
Engineering and Tires
- Pascal (Pa): The SI derived unit. It is small; therefore, Kilopascals (kPa) and Megapascals (MPa) are more common in structural engineering.
- PSI (Pounds per square inch): Extensively used in the automotive and aviation industries for tire pressure and hydraulic systems.
- Bar: Roughly equivalent to 1 atmosphere or 14.5 PSI, commonly used on tire pressure gauges in Europe.