This standard applies to the measurement of humidity of moist air from sea level to 3048 m (10@000 ft)@ within the drybulb temperature range of ?C50??to 160??(?C58??to 320??@ and within the dew-point temperature range of ?C50??to 99??(?C58??to 210??. This standard applies to methods for the direct measurement of wet-bulb temperature@ dew-point temperature@ relative humidity (RH)@ and humidity ratio. This standard requires determining the uncertainty of direct humidity measurements due to various sources of errors. PURPOSE This standard prescribes methods for measuring the humidity of moist air with instruments.