Exam 3 Flashcards
(138 cards)
1
Q
The depth below the surface where the circular orbits become so small that movement is negligible is called the
A
wave base
2
Q
The uninterrupted distance over which wind blows without a change in direction
A
fetch
3
Q
At the surface of the ocean the diameter of a wave orbital is equal to
A
wave height
4
Q
Generally, the greater the speed, the greater the
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wavelength
5
Q
How do you calculate celerity?
A
L/T
6
Q
restoring force for wind-generated waves
A
gravity
7
Q
three factors that influence wave height
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fetch, wind duration, and wind speed
8
Q
the time between two successive waves is called the
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period
9
Q
What is the ratio of H:L
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wave steepness
10
Q
Wind waves grow from what types of waves?
A
capillary waves
11
Q
In deep-water waves the water depth is greater than the ____ divided by 2.
A
wavelength
12
Q
As a deep water wave approaches a shoreline and becomes a transitional wave, its wave height _____ and its wavelength _______.
A
increases; decreases
13
Q
A Beaufort number of _____ is where we would begin to see the formation of whitecaps in the ocean.
A
3
14
Q
If we see orbital movement of water at a pynocline we are looking at _____ waves.
A
internal
15
Q
Waves in the surf zone begin to behave like shallow-water waves when _____.
A
wave depth = wavelength/20
16
Q
Wave formed on a river by a flood current.
A
tidal bore
17
Q
The angular distance of the Sun or the Moon above or below the Earth’s equatorial plane is called the ______?
A
declination
18
Q
When the Earth is at its greatest distance from the Sun, it is said to be at _____.
A
aphelion
19
Q
The difference between centripetal forces and gravitational forces is called the _____.
A
resultant force
20
Q
A neap tide has _____ tidal range.
A
low
21
Q
There is constructive interference between the lunar and solar tidal bulges during _____ tides.
A
spring
22
Q
The center of mass of the Earth-Moon system is called the ______.
A
barycenter
23
Q
Which of the following would you expect to find on a summertime beach?
A
a wide, sandy berm
24
Q
The section of the coast that is exposed at low tide and submerged at high tide is called the _____.
A
foreshore
25
Isostatic movement of a coastline might occur due to
removal of a big glacier in the area
26
Eustatic changes in sea level might include
increased glacial melting due to the climate change
27
Which of the following is found at a depositional shore?
deltas
28
Which of the following is designed to prevent or retard shoreline erosion?
seawall, beach nourishment, groin
29
In terms of erosion protection from wave action, seawalls
lead to erosion of sediment on their seaward sides
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Sediment is supplied to the coastal zone by
rivers, coastal erosion, local biological activity
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regular, long-period waves that have sorted themselves based on speed
swell
32
If you have a moon that is 7 days old (past new moon) what type of tide would we experience?
neap tide
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If you took a series of salinity measurements and found that salinity was constant at all depths in a particular estuarine location, you are probably in which kind of estuary?
vertically mixed
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_______ force - ________ force = ________ force
centripetal, gravitational, resultant
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A full lunar tidal cycle is _____ than a solar day.
+50 minutes
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A solar day is ____ than a full lunar tidal cycle.
-50 minutes
37
If the mainland is connected to an island by a sand ridge, we would term that feature a
tombolo
38
Why do waves converge on headlands?
wave refraction
39
A tide that occurs when a spring tide corresponds with the moon in perigee is termed a
proxigean tide
40
4 types of armoring
groins, jetties, breakwaters, seawalls
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Groin definition and the problem with it
armoring built perpendicular to the beach which is made of large blocky/rocky material. Traps the sand and builds up the beach in the north, but causes erosion below it. Slosh, backwash moves in the south direction - lose sand south
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jettie
type of hard stabilization build in pairs - go long ways and have done major stabilization and they have caused massive buildup because they fill area with sediments and sand
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sea wall
remove beach as water strikes sea wall it is eroding sand below sea wall and it will collapse. Wave activity will undermine sea wall, so it will have to continually be repaired. Loses beach for public.
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Alternatives to armoring?
construction restrictions, relocation, beach replenishment
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sun's declination to earth
23.5 degrees
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declination of moon to earth
28.5 degrees
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apogee
point at which moon is furthest from earth in its orbit
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perigee
point at which moon is closest to earth in its orbit
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tidal range is ______ at perigee
highest
50
Apogee has what affect of GF
decrease
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perigee has what affect on GF
increase
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aphelion
sun is furthest from earth in its orbit
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periphelion
sun is closest to earth in its orbit
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center around which the tide rotates
amphidromic point
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connects all locations that are experiencing high tide at one time; can be strange in shape but it has to do with the basin
cortidal lines
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tidal datum
reference point for the tidal height; not always at sea level
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diurnal
one high and one low tide per day
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semidiurnal
2 high, 2 low tides a day
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mixed
2 high, 2 low tides a day - tidal range is different - common
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when water is moving out of the system; can be very strong; tides near shore; leads toward low tide
ebb tide
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when water is moving into the system; tides near shore; leads toward high tide
flood tide
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little movement
slack tide
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most extreme tides - location
Bay of Fundy, Nova Scotia - 15m
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How do we predict tides?
relative distance, position of moon, declination, where are the amphidromic points
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What influences predicted tides?
weather patterns, storm surge, tsunami, strong on-shore winds, high and low pressure systems, strong wind patterns
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proxigean tide
spring tide at perigee; every 1.5 years; can cause coastal flooding
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spring tide
full moon; new moon; when tidal range is greatest
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neap tide
moon is at a right angle; low tidal amplitude; tidal range is at its lowest
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Nadir
point that earth is furthest to the moon; lowest gravitational forces
70
Zenith
point that earth is closest to the moon; high gravitational forces
71
gravitational force arrows point where
toward the center of the moon
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centripetal force arrows
center seeking; what keeps planet in orbit; same at all points; points straight
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resultant force
Fg - centripetal force ; this is what impacts tides; vectors point towards zenith or nadir; top and bottom arrows point into the center of earth
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tidal period
12 hours and 25 minutes
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lunar day
24 hours and 50 minutes
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solar day
24 hours
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syzygy
when earth, moon, and sun system are aligned; creates high tidal amplitudes; highest highs and lowest lows; during spring tides
78
what is the average tidal range in Jax
3-6m
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disturbing force
whatever caused the wave to form; wind, body, pretty much anything
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Where are ocean waves formed?
air-water interface
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Where are atmospheric waves formed?
between 2 air masses of differing densities
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Where do internal waves form?
water-water interface
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What causes internal waves?
tides, turbidity currents, ship movements
- high density bottom water and low density surface water
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wave base
point at which there is negligible water movement due to depth ; 1/2(L) - tells u depth of ocean that will be impacted
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Stoke's Drift
slight movement of water forward along the path of the energy transmission
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How do we classify waves?
disturbing force, are they still under disturbing force, what restores them, wavelength
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5 types of waves in increasing order
1. capillary wave
2. wind waves
3. seiche - long period waves that rock back and forth
4. tsunami
5. tide
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free wave
wave that is no longer under the force that created it ; tsunami
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forced wave
type of wave that is still under disturbing force ; tide
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deep water wave
waves that are found at a depth greater than 1/2 (L)
91
when steepness is greater than _____ what happens
1/7 < H/L
unstable and breaks - white caps
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Beaufort Wind Scale
wind scale and state of the sea; 0-12 ; 0 is flat ass calm; 12 is hurricane; 3 presence of white caps
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wave trains
free waves; group velocity is very slow; form series of rounded swells coming from offshore storm; progress forward, lose leading wave, gain new wave at the end of the train ; overall celerity of the group Cg = C/2
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constructive wave interaction
come together in phase and build each other up. 1m crest meets 1m crest = 2m crest
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destructive wave interaction
if out of phase, they will cancel
1mcrest meets .5m trough = .5m wave
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mixed wave interaction
waves of different lengths and heights; form rogue waves
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rogue waves
very dangerous, randomly large, rare waves coming in and against a powerful current; horn of Africa
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wave refraction
bending of waves as they approach shore; regions that hit shallow water first, slow down allowing rest of wave to catch up
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wave defraction
waves move around an obstruction; as waves strike the object they bend around the region, makes crossing area for waves beyond the island; lots of erosion
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wave reflection
wave strikes barrier, bounces back - may form standing wave ; oscillate around node
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3 types of breakers and characteristics
1. spilling - JAX, gradual slope, long distance, East Coast
2. plunging - steep slope, short distance, West Coast
3. surging - very steep, very short distance
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tsunami
seismic sea waves that move quickly and have extremely long wavelengths; caused by tectonic events; common in Pacific
103
shore
zone that lies between the low tide line and the highest area on land affected by strorm waves
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coast
extends inland as far as we have ocean related features
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coastline
region between the coast and the shore
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backshore
upper region of the shore that is above high tide line
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foreshore
part of shore that is exposed at low tide and exposed at high tide
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shoreline
water-land interface; moves
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nearshore
extends low tide shoreline to low tide breaker line
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offshore
zone beyond breakers
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longshore drift
movement of sediments parallel to shore driven by wave energy; longshore current (flow of water) moves particles up (angular) (swash) and straight back (flow) moving it in the direction of the current
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summer beach
wide, sandy berm; light wave activity, backwash not significant; swash pushes particles up but backwash doesnt necessarily bring it all back ; NO LONGSHORE BARS
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winter beach
heavy wave action; backwash dominates; narrow beach; longshore bars present
114
headlands have waves crashing on it called
defraction
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barrier islands
extremely long offshore deposits of sand that run parallel to coast; protect mainland from high wave activity; temporary features that developed about 18,000 years ago at the end of the last ice age
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Offshore bar theory
barrier island formation - waves crashing into the shadows build up sand and begin building the sand bar; sand bar will emerge and form barrier island
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Spit accretion theory
barrier islands formed from sediment from longshore drift. Drift accumulates to form spit or strip of land connected to mainland that juts out of land connected to mainland that juts out into the water.
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Submergence theory
water moves in on coastal ridges and separates them from the mainland
119
what kind of barrier island migration is happening now
transgressive migration - island moves back toward mainland - sea level rising
120
deltas
deposition of materials deposited at the end of the river; form in low energy areas; currents not too strong; broad continental shelf
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Arcurate Delta
Ganges River; river mouth arches out into the sea and the river splits many times
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Cuspate Delta
Ebro River; juts out arrowlike, does not carry a lot of sediment
123
Bird's Foot Delta
Mississippi; a lot of deposition and so the river juts out into the sea or gulf; carries a lot of sediment
124
3 types of coral reefs and their descriptions
1. atoll - specialized type of island found in the tropics; form from volcanic island
2. fringing - found against shoreline; grows seaward from shore
3. barrier - usually a lagoon that is separating the reef from the shoreline
125
how do atolls form?
1. on an active volcano, coral growth starts to builds up close to the shore
2. As the volcano becomes inactive and sinks, coral builds up more over time.
3. Eventually, island sinks below sea level but a thick section of coral builds up to stay close to surface, creating the atoll.
126
mangrove
type of halophyte (tolerant to salinity); 3 kinds black, red, white
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mangle
dense growth of mangroves
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overwash islands
dominated by red mangroves; surrounded by estuary or lagoonal water; excellent for bird habitat
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mangrove fringe
found along shoreline; protect shoreline and reduce erosion; dominated by red mangroves
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coastal plain estuary
Chesapeake Bay; formed when ancient glaciers melted and some of the streams and rivers covered with water as sea level rose - lots of volume
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fjord estuary
Glacier Bay; glacially carved; northern habitats where rocky coastlines are - glaciers melted sea water floods in; deep and steep
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bar built estuary
used to be St Johns; sand bars or barrier islands build up by ocean currents and waves create protected area fed by smaller streams and rivers
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tectonic estuary
San Francisco Bay; formed where tectonic activity sunk the land or the land is sliding by itself
134
vertically mixed
same salinity from surface to bottom but transition of salinity from fresh at the head to more saline at the mouth; shallow, low volume
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slightly stratified
salinity increasing from head to mouth; more saline at bottom than top; tend to be a little deeper
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Highly Stratified
deep deep, upper layer salinity increasing from head to mouth- surface waters low in salinity but marine at bottom
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salt wedge
high volume; lots of water coming out of head which forms a freshwater lens over the more saline water
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mixing salinity dependent on what 3 characteristics
shape of basin, river volume, range of tides
