What Are the Effects of Wind Speed on Wave Size?

Wind speed is one of the wind-related factors that combine to serve as a major determination of the size of waves. Wind speed does not determine a wave's size alone, though. Other wind-related factors include the size of the area that the wind covers, which is often called the fetch, and the amount of time that the wind continues to blow on an area of water.

  1. Initial Energy Transfer

    • When the wind blows, it begins to transfer its energy to the surface of the water that it strikes, creating small ripples in the water, according to Helene Schember, associate director of the Cornell Center for a Sustainable Future. As the wind continues to blow, the ripples grow larger, building on each other within the water, stirred by the wind.

    Waves Grow

    • As the ripples grow into waves, the wind blows on the backs of the waves. The increased size of the waves means that there is more area for the wind to strike and to affect, increasing the amount of energy transferred to the waves. The higher the speed of the wind, the more energy the waves receive and the larger the waves grow. When high-speed winds continue to blow on waves for an extended period of time, they prompt the waves to break, which feeds more energy into the wave system that has formed, according to Schember.

    Swells

    • When the wind is blowing at a particularly high speed offshore while also covering a large area, the result can be a swell, which is a long-lasting, large and powerful wave or series of waves. When a high-speed wind is applied to a large swath of water for a sustained period of time, it enables the wind to transfer a great amount of energy to the waves. This energy drives the waves to grow large and travel a long distance, even beyond the area where the wind is blowing, so that a windless day at the beach might feature very large waves built by high-speed winds miles away.

    Surfing Conditions

    • Wind speed is one of the elements that surfers study to project how favorable surfing conditions will be for them. Signs of strong wind can be indicators of great waves for surfers, as long as the wind is occurring in the right place. For instance, if you feel a high-speed wind while you are standing on the beach, it actually suggests bad surfing conditions because the resulting waves have an uneven size and do not maintain that size as they approach the shore. A high-speed offshore wind, on the other, maintains its size, making for better surfing conditions.