Weather Watch radars are very effective tools for the detection of rain. Bureau forecasters can interpret the patterns and intensity of the radar images to provide warnings of major weather events such as severe thunderstorms, tropical cyclones and areas of heavy rainfall.
Note that the radar does not "see" clouds, as cloud droplets are too small, but does see the rainfall which those clouds produce. These areas of rain "seen" by the radar are often called radar echoes. The radar may sometimes detect echoes from aircraft, areas of smoke/ash from large fires, swarms of insects, flocks of birds or even the ground or sea surface, when unusual atmospheric conditions bend the radar beam back down to the surface. As a result, there may be patterns on the radar images that do not represent falling rain.