Ws=p−ps0.621945∗ps Here ps represents the saturation pressure of water vapor in the absence of air at the given temperature and it differs slightly from the vapor pressure of water in saturated moist air.
Humidity ratio @ DBT = Humidity ratio at Saturation Wdbt=Ws Wdbt=14.691−0.430.621945∗0.43 Ws=Wdbt=0.0188
Relative Humidity (RH)
Partial pressure of Water vapour
Where, pw - Partial pressure of water vapour (VP) in psia W - Humidity ratio in lb/lb p - Standard atmospheric pressure at given altitude(sea-level) in psia (Refer Humidity Ratio calculation for details)