ocean

The gravitational pull of the sun and moon oscillates the surface of the oceans twice a day while the wind agitates it into waves. The surface of the sea exerts a frictional drag on the bottom layer of a wind blowing over it, and this layer exerts a frictional drag on the layer above it, and so on. The top layer has the keast frictional drag exerted on it which means that the layers of air move forward at different speeds. The air tumbles forward and finally develops a circular motion. This motion causes a downward pressure on the surface at its front, and an upward pressure at its rear, and this causes the surface to take on the form of a wave. The back of the wave tumbles forward but it moves back later and slows the forward movement at the front of the wave. The wave now grows bigger.