Abstract
In an examination of microwave data from the Nimbus 7 satellite, brightness temperatures were found that were much lower than those expected for the radiation emanating from rain-producing clouds. Every case of very cold brightness temperature coincided with heavy thunderstorm rainfall. The cold temperatures can be attributed to scattering by a layer of ice hydrometeors in the upper parts of the storms. Thus it appears that brightness temperatures observed by satellite microwave radiometers can at times distinguish heavy rain over land.
