ONR Science & Technology Focus
               Oceanography       Space Sciences       Blow the Ballast!       Teachers' Corner   
Ocean in Motion Ocean Habitats Ocean Life Ocean Water Ocean in Regions Research Vessels Resources

Ocean in Motion: Waves - Surf

In deep waters, only wavelength and wave period affect a waves speed. As the wave approaches shallow water, or water that is half the wavelength or less deep, the ocean floor begins to affect the wave's shape and speed. Wave height increases, and the crests become more peaked. As the steepness increases, the wave becomes unstable. The forward speed of the crest becomes faster than the speed of the wave, and the wave breaks.

We can describe breaking waves in three different ways: Surging Breakers, Plunging Breakers and Spilling Breakers. You see examples of these at the beach.

Surging Breakers Diagram
From "Ocean Talk" by Naval Meteorology and Oceanography Command.

Surging Breakers happen on beaches where the slope is very steep. The wave does not actually break. Instead, it rolls onto the steep beach. These kinds of breakers are known for their destructive nature.

Plunging Breakers Diagram
From "Ocean Talk" by Naval Meteorology and Oceanography Command.

Plunging Breakers happen on beaches where the slope is moderately steep. This kind of wave normally curls over forming a tunnel until the wave breaks. Expert surfers love this type of wave!

Spilling Breakers Diagram
From "Ocean Talk" by Naval Meteorology and Oceanography Command.

Spilling Breakers occur on beaches with gentle slopes. These waves break far from the shore, and the surf gently rolls over the front of the wave.

next page next page