Atmosphere (unit) for the purposes of specifying the physical properties of substances, “"standard pressure"” should be precisely . A pressure of 1 atm can also be stated as: Scuba divers and others use the word "atmosphere" and "atm" in relation to pressures that are relative to mean atmospheric pressure at sea level (1.013 bar). For example, a partial pressure of oxygen is calibrated typically using air at sea level, so is expressed in units of atm. The old European unit technical atmosphere (at) is equal to 1 kilogram-force per square centimetre (kgf/cm), Pa. Atmosphere (unit) The standard atmosphere (symbol: atm) is a
Dobson unit when plugged into the real gas law, the number density of air is found by using pressure, temperature and the real gas constant. formula_3 The number density (molecules/volume) of air at standard temperature and pressure (T = 273K and P = 101325 Pa) is, by using this equation: formula_4 With some unit conversions of Joules to Pascals, the equation for molecules/volume is formula_5 A Dobson Unit is the total amount of a trace gas per unit area. In atmospheric sciences, this is referred to as a column density. How, though, do we go from units of molecules per cubic meter,