Ocean Waves

1. Ocean Waves

2. Anatomy of a Wave • A wave is the motion of a form that carries energy from one place to another • The form is what moves, the material that the wave moves through does not move much. • The wave form is characterized by: • Amplitude, measured from midline • Wavelength, measured between identical points of motion • Frequency, a count of how many wavelengths pass a fixed point in 1 second

3. Anatomy of a Wave • The speed of most waves is determined by the material that the wave is moving through. • The speed is calculated using: • Where • v is velocity, in m/s • f is frequency, in Hz • λ is wavelength, in m

4. Anatomy of a Wave • Ocean waves are generated when wind flows over water • The wind drags across the water, starting the formation of a wave • If the wind is fairly continuous, then the wave built will be larger • A group of large wave is called a Swell

5. Wave Size • Factors that affect the size of a wave: • Wind speed • Faster wind kicks up larger waves • Duration of wind • Long duration, stead winds create larger waves • Fetch • Distance available for the wind to work over • Large fetches produce large waves

6. Waves and the Shore • As waves reach shallower water they begin to break up • Bottom of wave scrapes along seafloor, and slows down • Top continues to move forward quickly, and begins to curl over • Once top is too far ahead, the wave breaks

7. Waves and the Shore • After the wave breaks, the water is drawn back away from shore by undertow currents • If the waves are large enough, the undertow currents can develop into rip currents • Very strong undertows that pull water directly back into the sea • Strong enough to break through incoming waves

8. Waves and the Shore • As waves approach the shore, they nearly always bend to head straight into shore • This bending causes water beneath the waves to flow parallel to the shoreline. This can create longshore currents • Longshore currents help to straighten out shorelines, develop sandbars, and barrier islands