On the Calibration of the Radiometer for Longwave Radiation (I)

The effects of the environmental wind and temperature fields on the measurement of net flux of radiation by conventional net radiometers are examined. The variation in output of the net radiometer due to the wind field exceeds ten percent for both FUNK'S net radiometer ("wind shield-type" net radiometer) and GIER and DUNKLE'S net radiometer ("ventilation-type" net radiometer) in the ranges of wind speeds, vertical temperature gradients and incident radiation fluxes concerned. And as for FUNK'S net radiometer the more accurate value of net flux of radiation is expected to be obtained in the windy condition rather than in the calm condition. The devices hitherto available for calibrating net radiometers for longwave radiation are discussed in brief and our new device is presented.