Bar

The Bar [bar] is an allowed unit of pressure outside the SI system. Reference value is the coherent derived SI unit Pascal Pa. It is valid: 1 bar = 10⁵ Pa = 100000 Pa = 0.1 MPa. The standard value for the atmospheric pressure (caused by the weight of the air) is 1.01325 bar at 0 °C on sea level (standard elevation zero). The atmospheric pressure is measured with the so-called barometer; the atmospheric pressure decreases with increasing elevation level.