What Causes Waves to Break?

Is All Wave Breaking Caused By the Same Forces?

Most of us are familiar with the concept that waves break as they near the shore and that they often break right at the shoreline. There are, however, two distinct forces that cause waves to break, and not all waves break at or near the shoreline. In fact, waves can break in the middle of an ocean or lake, given the proper conditions and forces. This is due to the fact that waves can break either due to increasing shallowness in the water or because of contrasting wave patterns.

How Do Waves Break Due to Contrasting Wave Patterns?

When waves in one body of water are not all heading in one direction, it becomes inevitable that those waves will begin to run into one another. This is called a contrasting wave pattern. As the waves, moving in different directions, collide with one another, they combine their energy and create turbulent water. This can cause the crest of the waves to become so tall that they cannot be supported. When this occurs, no matter what the location, the waves in question will break. This is how waves break in the middle of large bodies of water.

How Do Waves Break Due to Increasing Shallowness?

This is the most familiar way in which waves break. Most people have seen waves breaking on the shoreline of an ocean or lake. This occurs because the waves are traveling into ever more shallow depths as they approach land. This causes the crest of the wave to emerge higher and higher out of the water, as the wave essentially gets "pushed" by the bottom ever higher. Once the crest of the wave becomes too high and the steepness of the wave becomes too great, the wave cannot retain its shape any longer. This causes the wave to collapse in on itself, or "break."

Resources

• More Information on Wave Action and Breaking