Construction and Evaluation of a Miniature Net Radiometer

Abstract

The miniature net radiometer was constructed by enclosing a blackened thermal transducer within four polystyrene radiation windows. The outer two radiation windows were hemispherically shaped (one-inch radius) so that the response to varying angles of incidence would follow the cosine law and precipitation runoff would be facilitated. The miniature net radiometer was calibrated in the laboratory in a chamber capable of simulating both solar and terrestrial radiation, and was found to be equally sensitive to both. The response to varying angles of incidence follows the cosine law. The output is not affected by wind or ambient temperature, and the size of the instrument enables its use to measure net radiation close to a surface or within a, plant canopy without appreciably altering the net radiation by shading.