8th grade Waves

1. WAVES

2. Waves
 A wave is a rhythmic movement that carries energy
through matter or space caused by the varying
speeds of winds.
 The crest is the highest point of a wave and a
trough is the waves lowest point.
 The distance between two adjacent crests equals a
wavelength.
 The height of a wave is the difference between the
crest and the trough.
 The amplitude of a wave is half of the waves
height.

4. ---

5. FREQUENCY
 The number of waves that pass a point in a certain
amount of time.


6. Wave Size
Depends on the strength of the wind and the length
of time it blows.
Gentle breeze = ripples
Stronger winds = lager waves
Wave size also depends on the distance over which
the wind blows.
Longer distance = Bigger wave

7. Wave movement
 Waves makes water appear to move forward, but
unless the wave breaks onto a shore, all water
returns close to its original spot after the wave
passes.
 Only the energy in the wave is moving forward not
the water.
 When a wave does crash onto a shore that wave is
called a breaker. This collapsing of a wave is what
propels a surfer back toward the shore.

8. Tsunamis
Not all waves get their energy from wind.
Some like Tsunamis are caused by earthquakes
beneath the ocean floor.
Most common in the pacific Ocean striking Alaska,
Hawaii and Japan

9. Affects on Shore
Longshore Drift
Rip Current

10. Longshore Drift
 Water washes up the beach at an angle carrying
sand grains
 Water and sand then run back down the beach
 Waves slow down and deposit sand on shallow
underwater slope = SANDBAR

11. RIP CURRENT
 Sandbar traps water flowing along the shore
 Some water breaks through the sandbar and flows
back down the sloping ocean bottom.
 The rush of water the flows back to sea is
= RIP CURRENT

12. WAVES & BEACH EROSION
 Waves shape a beach by eroding the shore in some
places and building it up in others.
What protects from Erosion??
 Barrier Beaches
 Sand Dunes
 Groins