# wave tidal wave by liaoqinmei

VIEWS: 6 PAGES: 30

• pg 1
```									Ocean Waves
 wave a periodic disturbance in a solid,
liquid, or gas as energy is transmitted
through a medium
 two basic parts—a crest and a trough
 wave period the time required for two
consecutive wave crests to pass a given
point
 wave height: vertical distance between
crest and trough
 Wavelength: distance between two crest
or troughs
Wave Energy
 Longer wind blows the more energy is
transferred into the water = larger waves.
 Wave movement:
◦ Energy in waves move from water molecule
to water molecule in the direction of the
wave
◦ circular motion
◦ in a single wave period, each water particle
moves in one complete circle
◦ Only the energy not the water moves across
the surface of the ocean.
Wave Size
   Three factors determine the size of a
wave.
◦ Speed of the wind, the length of time the wind
blows, and fetch.
◦ fetch the distance that wind blows across an
area of the sea to generate waves
   Whitecaps:
◦ When winds blow the crest of a wave off
◦ reflect solar radiation, they allow less
Waves and the Coastline
   Breakers
◦ Wave moves into
shallow water.
◦ The bottom of the wave
is slowed by friction
◦ The top of the wave
continues to move at its
original speed.
◦ the top of the wave
topples over and forms a
breaker, a foamy mass of
water that washes onto
the coastline.
Start of Wave Sequence
End of Wave Sequence
   Refraction:
◦ The bending of the
wave crest in response
to changes in wave
speed
◦ Shallow ocean water =
slower speeds
◦ Deeper ocean water =
faster speeds
Undertows and Rip Currents
   Undertow:
◦ Water carried onto a beach by breaking
waves is pulled back into deeper water gravity
   Rip currents:
◦ form when water from larger breakers
returns to the ocean through channels that
cut through underwater sandbars that are
parallel to the beach.
Rip Current
Longshore Currents
 currents form when waves approach the
beach at an angle
 currents flow parallel to the shore.
 Great quantities of sand are carried by
longshore currents
 These sand deposits form low ridges of
sand called sandbars.
Longshore Currents

geocaching.com
Longshore Currents

sci.uidaho.edu
Tsunamis
 giant seismic ocean waves
 Most are caused by earthquakes on the ocean floor, but
some can be caused by volcanic eruptions and underwater
landslides
 Nick name is tidal wave, but they are not caused by tides
 has a tremendous amount of energy
◦ In open ocean water they travel at a rate of around 760Km per
hour or 483mph, that similar to the speed of a jet aircraft.
 Not dangers in open water, but when they come into
shallower the energy is transferred into height = destruction
 The arrival of a tsunami may be signaled by the sudden
pulling back of the water along the shore
Tsunami

tsunamis.com

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