Name: ________________________________Date: _________________Period: __________
Waves: Motion in the Ocean
Ocean waves are disturbances. They transmit energy through the water while transferring very little
mass.
Ocean waves have crests and troughs, or highs and lows. The difference between a high and low is
defined as wave height. Wave amplitude is half of the wave height because amplitude is defined from
the zero line to either the wave or the trough.
Wavelength is the horizontal distance between a point on one wave and the comparable reference
point on the next wave. From one crest to the next crest.
A wave period is defined as the time it takes 2 successive crests to pass a stationary point.
1. Draw an ocean wave with 2 crests and 2 troughs and label the following: crest, trough, wavelength,
wave height and amplitude.
Anatomy of a wave:
A wave in the open ocean that does not interact with the bottom is called a deepwater wave, which is
defined as any wave where the water depth is greater than half the wavelength. The orbital motion of a
wave of a wave (the bobbing up and down that occurs at the surface) impacts the water to a certain
depth, but it’s not an infinite depth.
2. Define celerity: ____________________________________________________________________
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Types of Deep water waves
3. There are 2 main types of deepwater wave: capillary waves and wind waves.
Define Capillary waves: __________________________________________________________________
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Define Wind waves: ____________________________________________________________________
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Waves are classified by the disturbing force that creates them.
4. Identify three factors that control the variety and size of waves:
a. __________________________
b. __________________________
c. __________________________ = Fetch
5. What is the Beaufort scale? _________________________________________________________
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Waves do not stop when the wind stops blowing. Waves become more regular and well developed as
they spread away from the windy area .
6. A mature rolling wave that has left the area of development and propagates across the sea surface is
called a(n): ______________________
Waves come from the stormiest parts of the ocean. For the most part, large ocean swells start out in
either the high northern latitudes in the North Pacific or the high southern latitudes of the Southern
ocean.
Breaking waves
As a wave approaches shallow water, the orbital motion of the deepwater wave starts to drag on the
bottom, moving sediments back and forth or dragging on the rocks and the reef. This motion causes the
wave to slow down and become more peaked. Waves break where the ratio of wave height to water
depth is about 3:4. Due to circular orbits, the top of the wave is moving faster than the bottom as water
shallows, so it spills over.
There are 3 type of breaking waves, and they depend specifically on the characteristics of the slope and
shape of the ocean bottom where the wave is coming into shallow water.
7. 3 Types of Breaking Waves:
Type of wave:
Shape and slope of ocean
bottom:
Draw a picture of the wave type:
Rogue Waves and Tsunami
Tsunami and rogue waves are special classes of destructive waves capable of traveling long distances
across the ocean to strike with little warning. Tsunami result from the sudden displacement of the ocean
floor and overlying water due to an earthquake or landslide. Tsunami have wavelengths of hundreds of
kilometers and therefore travel according to the rules of shallow-water waves- even across the deep
ocean at ultrahigh speeds. Rogue waves are single waves that form by constructive interference of 2 or
more swells; they can reach heights of 100 feet or more creating a hazard to ships at sea.
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Waves can be a tremendously destructive force.
Tsunami and rogue waves are special classes of destructive waves that form by different
processes: they are not simply wind waves that have become out of control.
The research vessel James C. Ross sailed in the roaring forties, which is an area that is near
Antarctica in the Southern Ocean. This area has ferocious weather that causes the heaviest seas
on Earth.
Very large waves form where fetch is great; in the Southern Ocean, for example, the westerly
winds circle Antarctica continuously, creating large building seas. The height of these large
waves can reach 15 meters (50 feet), and their wavelength is so great that they present a hazard
to large ships that have been built to withstand such seas.
8. Explain the difference between a rogue wave and a tsunami wave: _________________________
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9. Research and identify two historical encounters between a sailing vessel and a rogue wave
include the date, name of vessel and the outcome:
a. ___________________________________: _________________________________________
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b. ___________________________________: _________________________________________
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10. What is the origin of a tsunami? _________________________________________________
11. What is another term for a tsunami wave:_________________________________________
Tsunami is a combination of 2 Japanese words: tsu- harbor and nami- wave. A tsunami is a harbor
wave, and it was given that name at least 1000 years ago in Japan because these were the waves
that overwhelm even the protected harbors, the regions where water doesn’t normally occur.
Tsunamis are not tidal waves; they have nothing to do with the tides. They are mainly generated by
a specific type of event.
12. Circle the term in bold that makes the statement correct:
Convergent / Divergent / Transforming plate zones are the sources of virtually all the large tsunami
that have occurred in recorded history.
13. Describe what is occurring at the plate boundaries where a tsunami originates: ________
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14. Give a brief description of the following tsunami events including casualties, environmental
affects and location:
2004: _____________________________________________________________________________
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2010: _____________________________________________________________________________
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2011: _____________________________________________________________________________
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15. What is a Dart Station and what its association with a tsunami? __________________________
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