Atmosphere (unit)

The physical atmosphere is since January 1, 1978 are no longer legal unit of pressure, the unit symbol is atm.

Etymology

The term derives from the Greek ἀτμός atmosphere ( Atmos ) = vapor, mist, breath and σφαῖρα ( sphaira ) = Ball ( Latinized SPHAERA ) ago. The printing unit is based on the size of the normal air pressure at sea level, thus corresponds to the caused by the gravitational force of the Earth's atmosphere pressure, hence the name.

Definition

A physical atmosphere is defined as 760 Torr. This corresponds to 101325 Pa = 1013.25 hPa = 101.325 kPa.

In order to