Relative Humidity Formula
Relative humidity is a ratio, expressed in percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated.
Example
Problem: If there are 10 grams of water vapor per one kilogram of a parcel of air, what is the relative humidity at 25°C?
Solution: According to the graph on the previous slide, the maximum amount of water vapor the air can hold at 25℃ is 20g/kg.
rH = 10g/kg ÷20g/kg = 0.5 x 100 = 50% Relative Humidity