The purpose of this research was to increase knowledge of the physical processes that govern wind characteristics over ridges and, subsequently, to improve empirical and numerical for estimating wind velocities over ridges. These objectives were achieved by conducting a wind-tunnel study of the flow field over triangular-shaped and sinusoidal-shaped ridge models with varying upwind and downwind slopes under various thermal stratification conditions. A simple technique was developed to predict the velocity-amplification profile above a ridge crest for an arbitrary ridge slope. Largest speedups were measured for the steepest symmetrical ridge which did not cause flow separation. Criteria for flow separation over ridges are provided in this report. Applicability of the results for ridges with finite width is discussed.