The Infrared Radiation Temperature Correction for Spherical Temperature Sensors

Abstract

The steady-state radiation temperature correction for a spherical temperature sensor, defined as the difference between the observed sensor temperature and the true air temperature, is computed for clear nighttime conditions in terms of five meteorological and physical parameters: sphere diameter, wind speed, observed sensor temperature, total incident radiation, and the absorptivities and emissivity of the sphere. The range of values encompassed by these parameters are, respectively, 0.001 to 0.1 cm, 0 to 400 cm set?1, 270 to 300K, 0.009 to 0.020 cal sec?1 cm?2, and 0 to 1. The infrared radiation incident on a sphere in the boundary layer of the atmosphere is related matic- matically to the radiation observed by a flat plate type of radiometer. The derived relationship is based on previous measurements of the spatial distribution of the intensity of infrared sky radiation. Numerically, the radiation temperature correction is determined by using a sequence of three graphs in-corporating the various parameters. The correction, to be added to the observed sensor temperature, varies from less than 0.01K to 3K.