1. WAVES

2. Waves are energy moving across the ocean
Waves can be caused by 3 things:
A. Wind (Wind-driven waves)
B. Moon’s and Sun’s gravitational attraction (Tides)
C. Earthquakes, volcanic eruptions, landslides, meteorites (Tsunami’s / Seismic Waves)

3. Wind-Driven Waves 2. The size of a wind driven wave is determined by:
a. time the wind blows
b. the speed of the wind
c. Fetch – distance over water that the wind blows

4. Characteristics of waves
3. Characteristics of waves include:
a. Crest – the highest point of a wave
b. Trough – the lowest point of the wave
c. Wavelength (λ) – Distance between successive (2) crests or successive (2) troughs
d. wave height- distance between a crest and a trough

5. e. Still water line – level of the water if there was no wind
f. Amplitude – ½ the wave height; the distance between the crest or the trough and the still water line
g. Frequency – the number of waves that pass a particular point in a given time period (waves/sec)
h. Period – the time it takes for two successive waves to pass a particular point (sec/wave)
i. Speed – wavelength/period

6. Wave Characteristics Still-water line Wavelength Crest Wave height
Trough
Amplitude

7. Types of Water Waves
Wind-driven (capillary) wave – small ripples less than 1” tall, restoring force is surface tension
Wind-driven (gravity) wave – waves greater than 1” tall, restoring force is gravity
Seismic wave (tsunami) – caused by earthquakes, volcanic eruptions, landslides, and meteorites. Restoring force is gravity.
Deep water – long wavelength and short amplitude
A boat at sea may not even notice the tsunami underneath
Shallow water – short wavelength and high amplitude
Wave height increases dramatically depending on shoreline topography

8. Tides – extremely long wavelength, caused by gravitational attraction between earth, moon, and sun and centrifugal force (due to Earth’s rotation). Restoring force is gravity and Coriolis effect.

9. Wave Interaction Constructive interference Destructive interference
Occurs when the crest of waves coming from two directions coincide and the resulting wave crest is higher than either one was
Maybe an explanation for rogue waves
Destructive interference
Occurs when the crest and troughs from two waves coincide and the resulting wave is basically cancelled out.

10. Orbital Wave Motion
Deep water wave – water particles move in a circular orbit and the size of the orbit decreases with depth
Little to no water movement at a depth greater than ½ the wavelength.

12. Shallow water wave – orbitals become flattened as water becomes shallow and the wave “feels” bottom
When water depth is less than ½ the wavelength the top of the wave moves forward faster than the bottom of the wave and it “breaks”

15. Types of Breakers
Spilling breakers – water from the top of the wave spills or tumbles down the front of the wave
Most waves on Miami Beach are this type
Found when shorelines are gently sloped

16. Plunging breakers – is formed when the wave crest curls over an air pocket and collapses
Type preferred by surfers in Hawaii and California
Found in areas where the shoreline is steeply sloped

17. Surging breakers – formed when the shoreline is more like a wall that rises out of the water and so the wave is not slowed down but surges into shore
can be very destructive