Ocean Waves: Formation and Movement

1. Bell work • Imagine you are floating in the ocean 1 km from shore, which is north of you. There is a surface current flowing east. Are you more likely to travel north with the waves toward the shore or east with the surface current? Draw a diagram to illustrate your answer, and record your explanation in your science journal.

2. Ocean Waves

3. Objectives • Identify the parts of a wave. • Explain how the parts of a wave relate to wave movement. • Describe how ocean waves form and move. • Classify types of waves.

4. Waves • A Wave is a rhythmicmovement that carries energy through matter or space. • In oceans, waves move through seawater

6. Waves Caused by: • Wind • Earthquakes • Gravitational force of the Moon and Sun.

7. Parts of a Wave • Crest – highest point of a wave • Trough – lowest point of a wave • Wave Height – vertical distance between the crest and the trough • Wavelength – horizontal distance between two crests or two troughs

8. Wavelength Crest Wave Height Still Water Trough Wave Parts

9. Wave Formation and Movement • Most waves form as wind blows across the water’s surface and transfers energy to the water. • As the energy moves through the water, so do the waves. But the water itself stays behind, rising and falling in circular movements.

10. Formation and Movement of Ocean Waves Click below to watch the Visual Concept. Visual Concept

11. Wave Movement • When a wave passes through the ocean, individual water molecules move up and down but they do not move forward or backward with the wave.

12. Waves Caused by Wind • When wind blows across a body of water, friction causes the water to move along with the wind. • Wave Height depends on – • Wind speed • Distance over which the wind blows • Length of time the wind blows

13. w a v e l e n g t h (m) = w a v e s p e e d (m/s) w a v e p e r i o d (s) Specifics of Wave Movement • Waves not only come in different sizes but also travel at different speeds. Wave speed is calculated by using the following equation:

15. Wave Movement • When a wave breaks against the shore, the crest outruns the trough and the crest collapses. • Called a breaker. • In this case, water does move forward and backward.

18. Wave Movement • When a wave crashes on the beach head on, the water flows back to the ocean underneath the new incoming wave creating an undertow. • Undertow- a subsurface current that is near the shore and pulls objects out to sea.

19. Wave Movement • When a wave hits the shore at an angle instead of head on it is called a long shore current. • Long shore current- a current that travels near and parallel to the shore line.

20. Wave Movement-Open Ocean waves • White caps- bubbles in the crest of a breaking wave. • These are seen during stormy weather.

23. Open Ocean Waves • Swells- rolling steady waves that travel great distances. • These are the types of waves during sunny nice days/nights.

24. Tsunamis • Giant ocean waves that form after volcanic eruption, submarine earth quake, and land slides • Waves that form when a large volume of ocean water is suddenly moved up or down.

25. Types of Waves, continued • Storm Surges are local rises in sea level near the shore that are caused by strong winds from a storm. • Winds form a storm surge by blowing water into a big pile under the storm. As the storm moves onto shore, so does the giant mass of water beneath it.

26. The End