Bar (unit) Bar (unit) The bar is a metric unit of pressure, but is not approved as part of the International System of Units (SI). It is defined as exactly equal to 100,000 Pa, which is slightly less than the current average atmospheric pressure on Earth at sea level. The bar and the millibar were introduced by the Norwegian meteorologist Vilhelm Bjerknes, who was a founder of the modern practice of weather forecasting. The International Bureau of Weights and Measures (BIPM) lists the bar as one of the "non-SI units [that authors] should have the freedom to use", but has declined to
Bar (unit) in depth. In sea water with respect to the gravity variation, the latitude and the geopotential anomaly the pressure can be converted into metres' depth according to an empirical formula (UNESCO Tech. Paper 44, p. 25). As a result, decibars are commonly used in oceanography. Many engineers worldwide use the bar as a unit of pressure because, in much of their work, using pascals would involve using very large numbers. In measurement of vacuum and in vacuum engineering, residual pressures are typically given in millibar, although torr or millimeter of mercury (mmHg) were historically common. Engineers that specialize in technical