1. Lesson 4.1: Waves
*Refer to Chapter 12 in your Textbook

2. Learning Goals: Label the anatomy of an ocean wave.
Differentiate between the various types of waves.
Describe the steps of a tsunami.

3. Anatomy of a Wave: Crest: highest point (top of the wave)
Trough: lowest point (bottom of the wave)
Wave Height: measured from crest to trough
Wavelength: measured from crest to crest

4. Anatomy of a Wave:

5. How Water Moves in a Wave
Water particles do not move forward, they move in a circular pattern
At a depth about equal to half the wavelength, the motion stops.

6. Waves Factors that affect size: Water depth Beach slope Wind speed
Fetch: distance of open water
the wind travels over

7. Waves
Types:
Wind generated
Earthquake generated
Tidal generated

8. Types of Wind Waves Capillary Breakers: Swells Surging Spilling
Plunging
Swells

9. Types of Wind Waves: #1 Capillary
Capillary: small waves, short wavelength, caused by surface tension

10. Types of Wind Waves: #2 Breakers
Breakers are medium- large waves that approach the shoreline
Wavelength decrease and wave height increases as waves approach the shore
Constant
Wavelength
Waves drag against the bottom
and wave length decreases

11. Types of Wind Waves: #2 Breakers
As the wave slows, its crest and trough come closer together
The bottom of the wave is slowed by friction and moves slower than the top
The top of the wave outruns the bottom and falls over. This collapsing wave is called a breaker.

12. Types of Breakers: 1. Surging:
Crest remains relatively unbroken, creating low foam
Best for skim boarding: riding the foam
Can have serious
effects during
storms

13. 2. Spilling:
The ocean floor has gradual slope, the wave will steepen until the crest becomes unstable
White water foam gently “spills” down the face of the wave
Best for beginner surfers,
swimmers, and boogey
boarders

14. 3. Plunging:
The ocean floor is moderately steep or has a sudden depth change, the crest of the wave becomes much steeper, curls over, and drops
Creates large crashing sound
Can have violent impacts
Best for professional
surfers ONLY!

15. Types of Wind Waves: #3 Swells
Swells: large waves in open ocean, long wavelength, large fetch
Type of waves that cause seasickness on boats
Measurement: A 10 ft swell rises 5 ft above sea level

16. Earthquake Generated Waves
Tsunami:
Largest waves, long wavelength, large fetch
Can also be caused by landslides, volcanic eruptions, & glaciers
Would feel normal in the
open ocean
NOT a tidal wave!