A thermocouple method for measuring relative humidity in the range 95-100%

Abstract

At high relative humidities a current of 30 mA through a 38 s.w.g. chromel-p/constantan thermocouple produces sufficient Peltier cooling to form a film of water on the junction which may then be used as the wet-bulb of a psychrometer. The wet-bulb depression can be read to 0-001[degree] C and in the range 97-100% relative humidity can be detected. After calibration over sodium chloride solutions the psychrometer was used to determine the water content/free energy curves of two soils, and good agreement has been obtained with previous determinations by other methods.