Abstract: This article introduced three methods for calculating dew-point temperature.The three methods include calculating dew-point temperature directly through the formula with dry-bulb temperature and relative humidity,calculating dew-point temperature indirectly through the formula with dry-bulb temperature,relative humidity,and environmental vapor pressure,and calculating dew-point temperature through the formula with dry bulb temperature,wet bulb temperature,and atmospheric pressure.This study analyzed the deviations between estimated dew-point temperature and observed dew-point temperature in Changchun,Xi'an,Wuhan,and Guangzhou.The results show that the direct and indirect calculating methods both have their merits.The error of the direct calculating method for estimating the dew-point temperature is within 0.5℃ when dry bulb temperature is between 0.0℃and 30.0℃ and relative humidity is between 40% and 100%.The direct calculating method is suitable for areas with higher temperature and relative humidity.Comparatively,the indirect calculating method for estimating the dew point temperature has a higher accuracy and the error is within 0.2℃,so this method can be applied in the future.

Key words: Dry-bulb temperature, Wet-bulb temperature, Relative humidity, Environmental vapor pressure, Coefficient of determination