Saturation vapor density
The saturation vapor density is the maximum density of water vapor at a given temperature. The concept is related to saturation vapor pressure. It can be used to calculate exact quantity of water vapor in a volume from a relative humidity Given an RH percentage, the density of water is given by. Alternatively, RH can be found by. As relative humidity is a dimensionless quantity, vapor density can be stated in units of grams or kilograms per cubic meter.
For low temperatures, SVD can be approximated from the SVP by the ideal gas law: where is the SVP, is the volume, is the number of moles, is the gas constant and is the temperature in kelvins. The number of moles is related to density by, where is the mass of water present and is the molar mass of water. Thus, we get = = density.
The values shown at hyperphysics-sources indicate that the saturated vapor density is 4.85 g/m3 at 273 K, at which the saturated vapor pressure is 4.58 mm of Hg or 610.616447 Pa.