Chapter 8
What type of wave behavior is shown in the illustration?
Diffraction
______ waves are abnormally high waves that are created by a special combination of questionable circumstances, appear suddenly, and appear unrelated to local sea conditions.
Episodic
What are the two types of energy in a wave?
Kinetic Potencial
Match the entity, program, or instrument used in detecting tsunamis to its description.
NOAA Leads tsunami detection in the Pacific DART Operates open-ocean instruments for detecting tsunamis Tsunameter Instrument for detecting tsunamis in the open ocean
Which of the following words best describe the speed of tsunamis in the open ocean?
Very fast
Which of the following is not a primary factor in determining the height of wind-generated waves?
Water depth
Tsunameters directly measure a change in the water ______ above the recorder on the sea floor in detecting tsunamis. This information is then relayed to an overlying buoy and then to a station via satellite.
pressure
wind waves are deep-water, generated by wind, restored by gravity, and move in a particular direction.
progressive
Forces that create a disturbance on the water are called forces, whereas restoring forces are responsible for returning the water to an undisturbed state.
generating
Waves that have gone through a transitional, or intermediate phase and are now in a water depth range between L/2 and L/20 are called waves.
intermediate
Tsunamis have ______ wavelengths and ______ periods.
long; long
The majority of tsunamis occur in the Ocean.
pacific
Long-period waves moving across the sea surface in a regular pattern of crests and troughs are called a(n) .
swell
If caught in a rip current, the best course of action for a swimmer is to ______.
swim parallel to the beach
A coastline with ______ has the best potential to be developed for wave power.
tall waves
A(n) is a seismic sea wave, taken from the Japanese word meaning "harbor wave."
tsunami
NOAA and DART are involved in the detection of ______ in the Pacific Ocean basin.
tsunamis
The Sperboy is an air-compression system from Great Britain that displaces air by an oscillating water column and then passes the air through generators to produce energy.
turbine
A wave will become too steep and break when the height-to-length ratio (or steepness) exceeds ______.
1:7
How long did it take the 2011 Japanese tsunami to reach South America?
About eighteen hours
The Universal Sea State Code is used internationally and relates wind speed to sea-surface conditions; it is adopted from the ______, initially created in 1806.
Beaufort Scale
True or false: A tsunami is a tidal wave.
False
True or false: Episodic waves are created from a well-understood set of conditions.
False
True or false: The water particles in deep-water waves are moving toward shore.
False
True or false: There is no way to escape a rip current once you are caught in one.
False
What happens when wave trains traveling in the same direction join together in phase—that is, wave crest coincides with wave crest?
Large-amplitude waves can be created.
Which ocean basin is the birthplace of most tsunamis?
Pacific
Surface tension is the restoring force for what type of wave?
Ripples or capillary waves
Which of the following waves is one that does not progress?
Standing wave
What happens to most of the water that surges on land from a tsunami?
The water that first raced up on land then returns just as destructively in the direction from which it came.
What happens to individual water particles in deep-water waves?
They move in a circular orbit but not toward the shore.
Tsunamis may go unnoticed by sailors in the open ocean ______.
because the wave's height is distributed over its many-kilometer wavelength
The alternations of low and high water in a standing wave are called ______.
antinodes
Plungers and spillers are known as , which form in the surf zone as water particle motion is affected by the shallowing of water depth.
breakers
The speed of a shallow-water wave depends only on ______.
depth
The height of the 2011 Japanese tsunami when it reached Japan ranged from approximately 8 to 39
meters
Standing waves oscillate about a point called a(n)
node
Wave trains are packets of waves with similar ______ and ______.
period; speed
currents are caused by the quick seaward flow of water, usually near the beach.
rip
Water that accumulates against the beach due to wave action commonly returns to the sea in narrow, swift-flowing regions known as ______.
rip currents
Tsunamis are ______ waves.
shallow-water
Rip currents are often a different color from the surrounding water because ______.
they carry turbid water seaward through the surf zone
energy can be harnessed by allowing the water to lift or rock an object, or to compress air or water in a chamber.
wave
A ______ surf zone offer more protection from waves because the energy is dissipated over a ______ distance.
wider; longer
When a deep-water wave approaches shore, it transitions to a shallow-water wave, and the water particle orbits change shape as they interact with the land. What is this interaction commonly known as?
"Feeling bottom"
Which of the following statements correctly describe the relationship between wave steepness, wave height, and wavelength?
- steepness decreases as wave height decreases - - steepness is equal to wave height divided by wavelength - steepness increases as wave height increases
The Japanese tsunami of March 11, , was the costliest natural disaster to date at $250 billion.
2011
Using the image, match the letter to the correct part of the wave featured.
A - Crest B - Trough C - Wave height D - Wavelength
What is the primary difference between standing waves in this open basin and those in a closed basin?
A closed basin will have a node at its center.
Which of the following best describes the speed of a tsunami in relationship to a wind-generated wave in the open ocean?
A tsunami moves much faster than a wind wave.
When a wave moves shoreward, it "feels bottom" and slows down. What other changes accompany the change in speed?
An increase in height A reduction in wavelength An increase in steepness
Which of the following conditions would be the best for wave power development?
Areas where large-amplitude waves are common
Where is the diameter of the circular motion of a water particle the largest in an internal wave?
At the density boundary (pycnocline) depth
Match the term with its correct description.
Breaker - Formed in the surf zone when water particle orbital motion is slowed at the bottom Plunger - Dramatic wave that breaks with a sudden loss of energy and splash Spiller - More common wave that collapses gradually with turbulent water and bubbles
Match the component of the following equation to calculate the speed of a wave to its correct description. C = LT
C - Speed L - Wavelength T - Wave period
Match the the type of interference, experienced when a wave train collides with another wave train, with its correct description.
Constructive interference - Similar waves approach from opposite directions, and their crests coincide. Destructive interference - Similar waves approach from opposite directions, and one's crests coincide with the other's troughs.
Match the wave term to its correct description.
Crest - Highest point of a wave Trough - Lowest point of a wave Period - Time for two crests or troughs to pass a stationary point Frequency - How many wave cycles pass a stationary point in 1 second Steepness - Wave height/wavelength
-water waves are found in water where D > L/2, and -water waves are found in water where D < L/20. Remember that D represents the water depth and L represents the wavelength.
Deep Shallow
Which of the following processes are responsible for the creation of internal waves?
Deep-ocean currents Low-pressure storm systems Propeller motion disrupting the pycnocline
Most waves in the open ocean are -water waves that transition into -water waves when they approach the coast.
Deep; Shallow
Of all the causes for tsunamis listed below, which is the most common?
Displacement of Earth's crust below the sea surface
Match the symbols to their meanings in the following equation of wave energy. E = 1/8 ρ g H2
E Wave energy ρ Water density g Acceleration of gravity H Wave height
There are many forces that influence waves; they are classified as either generating or restoring forces. Select all of the following that are generating forces.
Earthquakes Physical displacement Wind Pressure differences
What is the primary difference between standing waves in open and closed basins?
In a closed basin, the nodes are found in the middle; in an open-ended basin, at least one node is found at the basin's entrance.
What happens when a tsunameter detects a possible tsunami?
It continues to record changes in pressure every 15 seconds and transmits the data more frequently.
Which of these statements correctly describe the surf zone?
It is along the coast. It is shallow. It is variable in width.
Which of the following statements correctly describe the 2011 Japanese tsunami?
It was generated by a very large earthquake. It caused $250 billion in economic loss to Japan.
Match the tsunami event with its description.
Krakatoa Massive volcanic eruption in 1883 Sumatra Mega-earthquake in Indian Ocean in 2004 Japanese Mega-earthquake in Pacific Ocean in 2011 Alaska Earthquake in northern Pacific in 1946
Why do waves refract as they approach shore?
One end of the wave crest begins to feel bottom before the rest of the wave, and that end subsequently slows down first.
Aptly names for the movement of the animal it mimics, the ______ generates energy from waves when its hull is pitched back and forth, turning a flywheel which drives an electric generator.
Penguin
Which of the following statements correctly describe progressive wind waves?
Progress in a particular direction generated by wind restored by gravity
Standing waves that occur in natural basins are called .
Seiches
Which of the historic tsunamis was responsible for the most deaths?
Sumatra, 2004
______ is the restoring force for ripples or capillary waves.
Surface tension
Which of the following are restoring forces that influence waves?
Surface tension Gravity
What happens to the size of orbital water motion with increasing water depth?
The diameter of the orbit gets increasingly smaller with depth.
What is fetch?
The distance over water that the wind blows in the same direction
Why does a wide surf zone provide more protection from large storm waves than a narrow surf zone?
The energy of the waves is expended over a longer distance before reaching shore.
What happens to the energy in a tsunami as the wave encounters land, slows, decreases in wavelength, and increases in height?
The energy that was previously spread out becomes confined in a very tall wave.
What causes a wave to collapse or break?
The height to length ratio exceeds 1:7.
Which of the following is the best definition of the surf zone?
The shallow area along the coast where waves slow, steepen, and break
What happens to a tsunami when it encounters land?
The wavelength decreases. The wave slows. The wave height builds rapidly.
Which of the following statements regarding tsunamis are true?
The wavelength of a tsunami is extremely long. The period of a tsunami wave is long.
What happens to waves that move through a barrier with a small opening?
The waves are diffracted, and wave energy is spread out.
What three conditions come together at 40° to 50°S latitude to regularly produce large waves?
The winds are strong (fast) The winds have long duration The fetch is nearly continuous, as there are no large landmasses
Why is the area between 40° to 50°S latitude known for the production of large waves?
There are no landmasses to interfere with the strong winds of long duration.
What is the relationship between individual wave speed (C) and group wave speed (V) for shallow-water waves?
They are equal.
What happens to waves that are reflected off of a physical barrier?
They return in the general opposite direction from where they came and create different types of interference patterns with incoming waves.
True or false: The 2011 Japanese tsunami caused damage in California and Hawaii.
True
Orbital wave motion extends to ______.
a depth equal to one-half of the wavelength
Most of the damage on land caused by a tsunami occurs ______.
both when the water first races up on land and when it returns back into the ocean after about five to ten minutes
The speed of an individual wave is represented by the symbol C, which stands for the term .
celerity
Rip currents are often a different ______ from the surrounding water because turbid seawater is carried seaward through the surf zone.
color
The sudden rise or fall of Earth's below the ocean is the primary cause of tsunamis.
crest
Wind-generated gravity waves are divided into two categories based on the ______ of the water they travel in comparison to their wavelength.
depth
The speed of a deep-water wave (Cdeep) is ______ proportional to its period (T) and wavelength (L). Cdeep = 1.56 T or Cdeep = 1.25 √L
directly
There are various ways to use the energy of waves to generate power. One of the more traditional ways, which is used in many types of electricity generation, is allowing the moving water to ______.
directly power a generator
Wind , , and fetch are the three most important factors in controlling the height of wind-generated waves.
duration speed
The types of energy in a wave come from the ______ of the wave (potential) and the ______ of the water particles in their orbits (kinetic).
elevation; motion
The distance over water that the wind blows in the same direction is called .
fetch
The _____ of waves is(are) increased as storm winds circle around a low-pressure center, thereby increasing wave size.
fetch and duration
Forces that influence waves either create water disturbances or return the water surface to an undisturbed state. These are ______, respectively.
generating and restoring forces
In order to calculate the energy in wave, you need to know its (H), of water (ρ), and the acceleration of gravity. E = 1/8 ρ g H2
height density
The steepness of a wave is equal to ______.
height/length
The longer the wavelength, and the longer the wave period, the the speed of a wave.
higher
As a deep-water wave moves on shore, it becomes a(n) ______ before becoming a shallow-water wave.
intermediate wave
Waves formed at the pycnocline are called ______ waves.
internal
In an internal wave, the diameter of the circular motion of a water particle is ______ at the density boundary (pycnocline) depth.
largest
Storm centers are ______-pressure areas with winds that flow ______.
low; in a circular pattern
Winds blow in a circular pattern around a low-pressure storm center, and the waves generated from the winds ______.
move outward from the center
The group speed of a wave train is ______ that of an individual wave and is the speed at which wave energy is transported away from its source in deep water.
one-half
Deep-water waves travel in water that is deeper than ______, and shallow-water waves travel in water that is shallower than ______.
one-half their wavelength; one-twentieth their wavelength
Water particles in a deep-water wave travel in a circular path referred to as a(n) .
orbit
Disruptions of the ______ can result in the creation of internal waves.
pycnocline
Internal waves can be found at the ______.
pycnocline below the water surface
Which of the following characteristics correctly describe the Universal Sea State Code?
ranges from 0 to 9 based on the beaufort scale describes sea conditions based on wind speed
Waves may off a physical barrier, creating different types of interference patterns with incoming waves.
reflect
Waves bend, or , as they approach the shore at an angle, causing the more forward part of the wave crest to slow down.
refract
Which of the following describe the waves known as swell?
relatively fast long period regular waves and crests
The average depth of the ocean is less than one-twentieth of a tsunami's wavelength, so they are ______ waves.
shallow-water
Group speed is ______ the speed of each individual wave in a wave train.
slower than
The of a wave is equal to its wavelength divided by its period.
speed
A wave with no progressive motion is called a wave.
standing
The maximum possible height for a given wavelength is the measurement of a wave's .
steepness
Waves generated during severe can be 10 to 15 m high and 100 to 200 m long.
storms
Approximately how long did it take for the 2011 Japanese tsunami to reach Japan after the earthquake occurred?
thirty minutes
Wave are groups of waves with approximately the same period and speed.
train
Steepness is equal to ______ divided by ______, and steepness ______ as wave height decreases.
wave height; wavelength; decreases
Tsunami waves may go unnoticed by ships in the open ocean because they travel very quickly and have extremely long .
wavelength
What is another term used to describe the speed of a singular wave?
Celerity
What are seiches?
Standing waves that occur in natural basins
In deep water, water particles travel ______.
in an orbit
