Wind blowing across the surface of the water starts the wave. As the air touches the water, it slows down and drags across water molecules at the surface. Unlike solid molecules, which are bound tightly together, water molecules can move freely. These molecules move when the wind pushes them, transferring the energy of the wind and changing the surface of the water. The friction of air against water creates ripples.
As the water surface ripples, the wind can get a better grip. Wind pushes ripples, creating wavelets. Waves grow in length and height, but need space to grow. Wind moving across the surface of a pond creates disturbances no bigger than ripples and wavelets. Wind moving across an ocean creates bigger waves that travel further. The choppier the waters, the better grip wind can have to create larger and longer waves. The largest waves are found in the Indian Ocean, where winds blow constantly in one direction.
Waves do not remain on the surface of the water. Water molecules move in a circular pattern in the wave. Water moves up to meet the wave, is pushed forward by momentum and wind, then down into the depth after the crest and backwards in the wave's trough. As waves grow in length, they often grow in depth as well, with disturbances reaching as far as 50 meters below the surface.
Long, rolling waves can become short and choppy when they hit shallow waters. This happens when the bottom of the wave touches the bottom of the sea. Waves will bounce off dense objects, like rocks and shorelines. The disturbance in the motion of the wave creates shorter wave lengths. The water surface can become choppy as the wave breaks and slows.
Waves carry a tremendous amount of energy. Scientists have failed to harness their power because the size of equipment needed to capture wave energy is enormous. The powerful energy of the waves is another obstacle, as it becomes destructive and dangerous.