Waves are formed when the wind blows across the surface of the sea. The friction between the wind and the water pushes the water up creating waves.

The height and power of a wave depends on two factors:

• The distance it has had to travel across open water to reach the coastline
• The wind speed

The distance over which the wind has blown is called the FETCH.

The greater the fetch, the larger the wave as it has more time to gather energy.

Example: Waves from Brazil travel 10,000km before they hit the south west coast of England making them very powerful.