A time-dependent, primitive-equation numerical model is used to test the hypothesis that solar variations induce changes in the distributions of basic state variables at high levels in the atmosphere, and thus induce changes in planetary-scale wave structure at lower atmospheric levels. This mechanism was proposed to explain apparent atmospheric responses to solar activity. The changes are brought about in the model by a diabatic heat source, which is taken to be a simple representation of Joule dissipative heating. Lower atmospheric wave structure is found to be insensitive to solar-induced changes in the upper atmosphere. Such changes as do occur are limited to within 25 to 40 km below the level of maximum heating, and are also quite short-lived.