Atmospheric processes associated with water in the atmosphere

Equation of state for a perfect gas

The pressure (p), specific volume (V, volume per gram), and temperature (T) of a perfect gas are related by the equation of state:

(A249)

where m is the molecular weight of the gas and R^∗ is known as the universal gas constant, 8.3144 × 10⁷ erg g⁻¹ K⁻¹. This equation reflects the observations of experiments with gases embodied in Boyles’ Law i.e., PV = constant at constant temperature, Charles’ law, i.e. any gas at a given pressure expands uniformly with temperature, and Avagadro's hypothesis which states that at normal temperature and pressure (273.15 K and 1013 mbar) the molecular volume is the same for all gases, namely 22.415 × 10³ cm³. These three laws, as well as being true for a perfect gas, are nearly true for atmospheric gases.

Dalton's law states that in a mixture of gases, the total pressure is equal to the sum of the pressures which would be exerted by each gas if it filled the volume under consideration at the same temperature. Hence a...