Direct Calculation of Thermodynamic Wet-Bulb Temperature as a Function of Pressure and Elevation

A simple analytical method was developed for directly calculating the thermodynamic wet-bulb temperature from air temperature and the vapor pressure (or relative humidity) at elevations up to 4500 m above MSL was developed. This methodology was based on the fact that the wet-bulb temperature can be closely approximated by a second-order polynomial in both the positive and negative ranges in ambient air temperature. The method in this study builds upon this understanding and provides results for the negative range of air temperatures (2178 to 08C), so that the maximum observed error in this area is equal to or smaller than 20.178C. For temperatures $08C, wet-bulb temperature accuracy was 60.658C, and larger errors correspondedto very high temperatures (Ta$398C) and/or very high or low relative humidities(5%,RH,10% or RH . 98%). The mean absolute error and the root-mean-square error were 0.158 and 0.28C, respectively.