Download Ocean Waves

Ocean Waves
Essential Question:
How are waves formed and what are the
characteristics of waves?
What is a wave?
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A Wave is the movement of energy through a body of
water
Most waves form when winds blowing across the water’s
surface transmit their energy to the water
How do waves differ?
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Wave Size:
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The size of the wave depends on the strength
of the wind and on the length of time it blows
Gentle breeze = small ripples on the surface
Strong winds = larger waves
Longer distances that the wind blows build up
bigger waves
Wave Energy:
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Although waves may appear to carry water
towards the shore, the water does not actually
move forward
The energy of the wave moves towards the
shore but the water remains in place
How do waves move?
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As the wave passes, water particles move in a circular
path
They swing forward and down with the energy of the
wave, then back up to their original position
Winds affects the water at the surface more than it
affects the deep water
Below a certain depth, the water does not move at all
What are the characteristics of waves?
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Crest is the highest part of a wave
The horizontal distance between
crests is the wavelength
Waves are also measured by their
frequency, or the number of waves
that pass a point in a certain
amount of time
The trough is the lowest part of a
wave
The vertical distance from the crest
to the trough is the wave height
What are the characteristics of waves?
Click picture for animation
How do waves change near the shore?
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The white capped waves that
crash onto the shore are usually
called “breakers”
As the wave approaches the shore
the water becomes shallower
The bottom of the wave begins to
touch the floor causing the wave
to slow down
As the speed decreases, their
shapes change
Near the shore, wave height
increases and wavelength
decreases
When a wave reaches a certain
height, the crest of the wave
topples
Waves not formed by wind
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Waves can also be formed below the ocean surface
This type of wave is known as a tsunami and is usually caused by
an earthquake beneath the ocean floor
The abrupt movement of the ocean floor sends pulses of energy
through the water above it
When tsunamis reach the coast, they can be as devastating as an
earthquake on land
How do waves cause beach erosion?
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From day to day, waves remove sand and bring new sand
at about the same rate
Waves shape a beach by eroding the shore in some places
and building it up in others
Waves can carve rocky shorelines into tall cliffs and
arches
Self Check:
1.
How do waves form?
2.
Which wind could give more energy to water- a strong
wind or a gentle breeze?
3.
What is the name for the distance between the crest and
trough of a wave?
4.
Why do waves slow down close to the shore?
5.
What is the source of energy for a tsunami?