Abstract
In this paper a slab model for horizontally homogeneous, stable boundary layers is developed, where variations in mean quantities at the boundary-layer top and in mean shear are accounted for. A rate equation for the boundary-layer depth is derived from the integral conservation equation for mean kinetic energy. The stab model compares favorably with a second-order closure model in simulating evolution of a nocturnal boundary layer. The model is applied to the prediction of nocturnal jets over the Great Plains; it is shown that the jet intensity depends primarily on the surface cooling rate at sunset and on baroclinity.