CTS-9523249 Fernando This work will be a laboratory study, augmented by theoretical analysis, of turbulent flows that are of interest to environmental and climatic forecasting. Specifically the proposed work addresses two processes that are vital for the understanding of small-scale phenomena in oceans and the atmosphere. The processes identified for study are: a) the sinking of negatively buoyant fluid masses in the presence of background stratification and mean shear and b) the entrainment at the base of a turbulent mixing layer in the presence of vertical velocity gradients. The first study has application to the generation of strong gusts and horizontal wind shears close to the ground. A better understanding of these phenomena is paramount to aviation safety. The second study is aimed at improving the mixing parameterizations of mixed layer models. These models are in use for short term forecasting.