Accession Number : AD0419926

Title :   DEVELOPMENT OF A DEWPOINT HYGROMETER FOR ATMOSPHERIC SOUNDING,

Corporate Author : BENDIX CORP SOUTH BEND IND BENDIX PRODUCTS DIV

Personal Author(s) : Farrah,H. R. ; Vitale,A. A. ; Young,H. R.

Report Date : JUN 1962

Pagination or Media Count : 1

Abstract : This report describes the development of a thermoelectric-cooled, mirror-type dewpoint hygrometer for use in measuring dewpoint in the range of -80 C to + 50 C in altitudes between 100 K feet and sea level. The hygrometer operates on the principle that when the water vapor pressure directly over a dew or frost film is in equilibrium with the partial pressure of water in the sample passing over a mirror surface, the temperature of the dew or frost film is the dewpoint temperature of the sample. Under equilibrium conditions, the dew or frost film on the mirror has a constant thickness. The hygrometer, by photodetecting the film thickness and thermoelectrically controlling the mirror temperature, maintains the film at a constant thickness. The mirror temperature under these conditions is at the required dewpoint temperature. This instrument can be adapted for ballonsonde or rocketsonde use. It is small, reliable, has simple sampling requirements, and shows promise of being produced economically. This report describes all the aspects of development, design, and laboratory and environmental tests. (Author)

Descriptors :   (*HYGROMETERS, DEW POINT), (*ATMOSPHERIC SOUNDING, HYGROMETERS), INSTRUMENTATION, WATER VAPOR, PRESSURE, MIRRORS, TEMPERATURE, DEW, BALLOON EQUIPMENT, COOLING, THERMOELECTRICITY, MEASUREMENT, OZONE, REFRACTIVE INDEX, SPECIFICATIONS, HEAT TRANSFER COEFFICIENTS

Distribution Statement : APPROVED FOR PUBLIC RELEASE