An experimental study of turbulent entrainment at a density interface due to mean velocity shear is reported in this thesis. The model which is comprised of a layer of initially quiescent salt water contained in a finite size cavity of length 290 mm under a flowing layer of freshwater, represents ambient windflow over a cloud of dense gas lying in a recess in the terrain. The density ratio in the fullscale situation is retained in the model and the density profile is a step function.