MICROWAVE-SPECTRUM OF CUMULUS CLOUDS

The thermal radiation of cumulus humilis and cumulus mediocris clouds (a total of 180 clouds) was investigated at wavelengths of 0.81 and 2 cm. The ratio of the radiobrightness temperatures at these wavelengths is shown to vary depending on the situation within almost 60%. These variations are due to the excess in the intensity for lower frequencie s of the spectrum. This effect is attributed, within the framework of the theory of thermal radiation, to changes in the molecular relaxatio n times of water in finely dispersed drops. The effect should be taken into account in remote sensing of water and moisture contents in a cl oudy atmosphere.