Relative humidity is the ratio of the partial pressure of water in air to the partial pressure of water in air saturated with water at the same temperature, stated as a percentage:
Relative = Partial pressure of water in air
humidity Partial pressure of water in air
saturated with water at same temperature
Among aviators it is more common to express the moisture content of the air by giving the air temperature and its dew point, that is, the temperature to which the air must be cooled for the first drop of water to condense. The following atmospheric conditions have been reported:
Atmospheric pressure = 1.011 bar
Air temperature = 25.6°C
Dew point of air = 20.6°C
Determine the relative humidity of the air?
The data given below are available for water:
In Psub (ice) = 28.8926-6140.1/T in Pa
Ln Pvap (water) = 26.3026 - 5432.8/T in K