An Instrumented light plane was flow through three wave clouds formed at the upper boundary of the marine layer just upwind of a headland, Pt. Sal, along the California coast. Temperatures and vertical velocities were recorded continuously during two traverses through the waves. The mean height of the interface, wavelength, potential temperature of the marine layer, potential temperature of the overlying warmer layer, the wind speed and the phase speed of the waves were determined. These values are shown to be consistent with theory for gravity waves at an interface separating two autobarotropic layers.