This report examines the effect of convective turbulence on the dispersion of pollutants emitted from tall stacks in the AOSERP area. As an introduction to this subject the structure of the convective boundary layer is described. Recent models to account for the effects of convection on plume rise are then presented. The body of this report is devoted to a new model to describe dispersion under convective conditions when tall stacks are most likely to cause significant groundlevel concentrations. The model is applied to the Suncor and Syncrude stacks for selected meteorological conditions. In this connection, the relationship between model predictions and short-term observations is examined in some detail. Finally, suggestions for a field study to verify the model are provided.