(May 1979)
It is suggested that long-lasting co-rotating active longitudes on the Sun may be associated with small variations of the solar radiation reaching the Earth. The oscillations have a basic period of about 27 days and are not expected to have amplitudes greater than 0.1%. They result in a time-varying heat input to the Earth‘s continents and, since the land exchanges heat with the overlying atmosphere, this oscillatory heating process generates large-scale planetary waves, mainly of the Rossby-Haurwitz type, in the atmosphere.