Degree of saturation or percentage humidity

Degree of saturation or percentage humidity:

We have already discussed that the degree of saturation is the ratio of actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature (dry bulb temperature). In other words, it may be defined as the ratio of actual specific humidity to the specific humidity of saturated air at the same dry bulb temperature. It is, usually, denoted by µ.

Notes:

a). The partial pressure of saturated air (Ps) is obtained from the steam tables corresponding to dry bulb temperature

b). If the relative humidity,   is equal to zero, then the humidity ratio, W = 0, i.e. for dry air, µ = 0.

c). If the relative humidity,   is equal to 1, then W = Ws and µ = 1 Thus µ varies between 0 and 1.