1. Waves, Tides, and Currents
S6E3d – Explain the causes of Waves, Currents, and Tides

3. Waves
A wave is a rhythmic movement that carries energy through matter and space. In the ocean, waves move through seawater.

4. Anatomy of a Wave Crest – the highest point of a wave
Trough – the lowest point of a wave
Wavelength – the distance between two adjacent wave crests or troughs
Wave Height – the vertical distance between the crest and trough of a wave

5. Wave Diagram
CREST
WAVELENGTH
WAVELENGTH
WAVE HEIGHT
TROUGH

6. Causes of Waves
When wind blows across a body of water, wind energy is transferred to the water
If the wind speed is great enough, the water begins to pile up, forming a wave
The height of a wave depends on:
The speed of the wind
The distance over which the wind blows
The length of time the wind blows

7. Once set in motion, waves continue moving for long distances, even if the wind stops blowing
The waves you see lapping at a beach could have formed halfway around the world
Water remains in the same place as waves travel through it

8. Types of Waves Deep-Water Waves and Shallow-Water Waves
Deep-Water Waves – waves that move in water deeper than one-half their wavelength
Shallow-Water Waves – waves that move in water less than one-half their wavelength
Interact with the ocean bottom – causes waves to increase in height

9. Shore Currents
Undertow - a subsurface current that is near shore and that pulls objects out to sea
Flows in the opposite direction of the wave

10. Longshore Currents
Longshore Currents - a water current that travels near and parallel to the shoreline
Transport most of the sediment and pollution in beach environments

11. Open-Ocean Waves
Whitecaps - white, foaming waves with very steep crests that break in the open ocean before the waves get close to the shore
Usually formed during stormy weather and are short-lived
Swells – rolling waves that move steadily across the ocean
Longer wavelengths than whitecaps and can travel for thousands of kilometers

12. Tsunamis
Tsunamis – waves that form when a large volume of ocean water is suddenly moved up or down
Can be caused by:
Underwater earthquakes
Volcanic eruptions
Landslides
Underwater explosions
Impact of meteorite or comet

13. https://youtu.be/XTvkrLESrwU
Storm Surges
Storm Surges – a local rise in sea level near the shore that is caused by strong winds from a storm, such as those from a hurricane
Can be the most destructive part of a hurricane