Properties of Waves
Anatomy of a Wave
 Wave: a disturbance that carries energy
through matter or space
 Crest: the highest point of a wave
 Trough: The lowest point in a wave
Wave Length
 wavelength: the
distance between
any two
corresponding
locations on the
wave.
 Can be measured from:
 crest to next crest
 trough to next
trough
 from the middle of a
wave to the middle
of the next wave.
Amplitude
 The height of the wave from its center to either a crest
or a trough
Wave Period
 the amount of time for
one wave to pass by a
certain point.
 Calculate by dividing the
amount of time by the
number of waves that
pass by in that time.
 A surfer knows that the
wave period is important
to a good day of surfing.
He watches 20 waves go
by in 200 seconds. What
is the period of the
waves?
10 sec/ wave
Wave Speed
 How fast a wave moves
 Practice:
 Remember that
 The wavelength of an
rate= distance / time
 For a wave
 distance= wavelength
 Time= wave period
ocean wave is 10 m and
the period of the same
wave is 5 seconds. What
is the wave speed?
2 m/s
Types of Waves
 Ocean waves
 Sound waves
 Seismic waves (Earthquake)
 Light waves
 Electromagnetic spectrum
Ocean Waves
 disturbances of water surfaces caused by energy from
winds, earthquakes, or volcanic explosions
 An example of surface waves (waves forming at the
boundary between two different materials)
 Most ocean waves at the beach are created by wind
Breakers (above) crash to the beach in Myrtle Beach, South Carolina.
What actually happens when a
wave goes by?
 Ocean waves transfer energy rather than actually
moving the water along with them.
 When wave energy passes through water, the water
moves in a circular motion.
 Watch the beach ball in the following animation
 The beach ball moves in a circle while the energy of
the wave moves from left to right
What actually happens when a
wave goes by?
 The circles that the water
particles make get
smaller with depth
 The energy being
transmitted decreases
with depth
 Water particles move in a
circular pattern down to
a depth of ½ the
wavelength
What happens when a wave
reaches the shore?
 Water deeper than ½ the wavelength
 the energy of the wave moves forward
 the water stays in place.
 Wave approaches shore
 depth of the water is less
than ½ the wavelength
 the friction against the ocean floor slows the
wave down and shortens its wavelength
 The wave breaks and crashes on the shore.
Mavericks Big Waves
Mavericks QoD: 1/30
 How big are the waves at Mavericks?
 Are they dangerous?
 What causes the waves to get so incredibly big?
Why do big waves happen here?
 Waves start in the North Pacific during winter storms
 If the wind is blowing hard enough in the North
Pacific, the waves will have a
large amount of
energy when they reach California
Bathymetry of Mavericks
 Mavericks is in the
box
 Seafloor mapping
shows blue as
deepest
Bathymetry
 As waves approach Pillar
Point, the center of the
wave hits shallow water
before the sides
 The wave slows down in
the center, but not the
sides
 Because the wave speed
is different in the center
than the sides, the wave
becomes curved
 The wave height in the
center becomes much
larger than the sides
because the seafloor is
shallower there
Mavericks
Did you turn in your Article???
 Reasons not to procrastinate…
 Technical issues
 Technical FAILURES
 You might get sick
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then you find out that the article you found got lost in
your email, and then on top of that your brother needs
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Sources
 http://secoora.org/classroom/waves/fact-sheet/
 http://www.pwssc.org/education/media/
 http://geoinfo.amu.edu.pl/wpk/pe/a/harbbook/c_vi/c
hap06.html