A prototype FM–CW radar for atmospheric sounding and some of its applications are described. The prototype generates a signal whose frequency increases linearly from 1830 to 2160 Hz during a time interval of 10 s, the excitation being at intervals of 20 s. The principle of operation is based on the fact that received echos reflected from inhomogeneities at height h, will have a frequency lower by an increment of (df/dt) (2h/c) than that currently being transmitted. Typical data taken with the prototype are compared with analogous data obtained with a pulsed SODAR.