Behavior of Waves
Waves can bend when they encounter obstacles or changes on the sea floor.
- Refraction involves bending. Wave refraction starts when wave base starts to interact with the sea bed and slow the waves down, causing them to bend toward shore. Refraction occurs when wave swells approach the beach at an angle (Figure 10.25).
- Diffraction involves spreading (or dispersion) of wave energy. Wave diffraction refers to various phenomena which occur when a wave encounters an obstacle or change in geometry of the seabed. For example waves are diffracted when they when they pass an island, or when they pass a point or other structure, such as a jetty at the mouth of a harbor (Figure 10.26).
- Reflection (bouncing) involves crashing into a solid surface (such as a seawall or cliff) and reflecting back to sea. Reflection can result in standing waves—waves that move back and forth (oscillate) in a vertical position waves strike an obstruction head-on and then are reflected backwards in the direction they came from.