Why is there a diurnal cycle of precipitation over the oceans?

Using the Colorado State University general circulation model, simulated diurnal and semidiurnal variability of precipitation has been analyzed. At least four mechanisms have been proposed to account for the observed daily oscillations of precipitations over the ocean: direct radiation convection, radiation-dynamics-convection interactions, remote influence of the continents, and atmospheric tidal forces. Results indicate that neither land-sea contrasts nor cloudiness are necessary to produce daily variations of precipitations over the oceans. Clear-sky radiative effects, cloud-radiative effects, and the remote influence of the continents all turn out to play a role.