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29 Cards in this Set

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What kind of waves have the longest wavelengths? shortest wavelengths?
Tides can be viewed as extremely long waves.
Capillary waves have the shortest wavelengths.
What three main factors determine the maximum length and height of oceans waves?
1. Wind speed
2. Wind duration
3. Fetch (distance over which steady wind blows)
“Wave energy” is directly proportional to what?
Wave energy is directly proportional to wave height
What is the “height-to-length” ratio (H:L) at which waves break or form white caps?
If S=1:7, which corresponds to a 120° crest angle, the wave breaks
What are the four primary causes of a tsunami?
1. Earthquakes
2. Volcanic Eruptions (especially on sea floor)
3. Landslides (both into the oceans and undersea)
4. Meter, asteroid or comet impact
What is a typical wavelength, wave height, period and speed of a tsunami?
Period T= 10 to 20 min
Wavelenghth L= 100 to 200 Km
Speed C= 200 m/sec
Is a tsunami a “deep water wave” or a “shallow water wave?”
Tsunamis are shallow water waves
What is a “mega-tsunami?”
A very large tsunami-like wave caused by an explosive volcanic event, a very large meteor, asteroid or comet impact or very large landslides into a body of water that cannot disperse in all directions.
What are “internal waves?” What are “standing waves?” “What is a seiche?”
Internal waves- waves which form between water layers of different densities
Standing waves- when a progressive wave reflects back upon itself, the reflection motion cancels the forward motion, giving the net appearance of a non-progressive, or standing wave.
Seiche- the standing wave oscillation of an enclosed or semi-enclosed body of water that continues, pendulum fashion, after the generation force ceases.
Know the difference between “nodes” and “anti-nodes” in a standing wave.
In a standing wave, the periodic vertical oscillation of the water is between its antinodes and about its nodes.
What are the four probable causes of “rogue waves?”
1. Large storm at sea: Due to varying speeds, these wave trains meet and build on top of one another, through constructive interference and create a large rogue wave.
2. Focusing of Wave Energy: when storm forced wind waves travel in the direction opposite to that of a strong ocean current.
3. Normal part of wave spectrum: Rouge waves can excel those heights and occur far more often than theory predicts. The three explanations above can be explained by “linear models” but in reality ocean waves are “non linear”
4. Rouge waves can be explained by the use of the non-linear quantum physics “Schrodinger equations”
Is a “rogue wave” a deep water wave or a shallow water wave?
It is a shallow water wave
What is the difference between diurnal tides, semi-diurnal tides and mixed tides?
Diurnal Tides- have one high tide and one low tide per day
Semi-diurnal Tides- have two high tides and tow low tides of equal water level
Mixed Tides- have two high tides and two low tides of unequal water level
Know the difference between a flood tide and ebb tide.
Flood Tide- rising tide. It is the period of the tide between low water and the next high water
Ebb Tide- Falling tide; the period of the tide between high water and the next low water
Explain tidal currents and “slack water.”
Tidal currents are produced in costal areas during a rising or falling tide. These currents can become very fast and dangerous in areas of strong tides and low bottom slop. When a Tide “turns around” there is a period of slack water (a good time to bring in your boat)
Know the difference between a spring tide and neap tide and when they occur.
Spring tides occur near the times of the near and full moon, when the range of the tide is greatest. Neap tides occur near the times of the first and last quarters of the moon, when the range of the tide is least.
Why does the moon rise about 50 minutes later each day?
It takes the moon 12° to move 50 minuets. Thus, a point on the earth initially aligned with the moon. Must rotate 372° to find itself again aligned with the moon. Time required to complete the 372° is 24 hours 50 minuets or 1 lunar tidal day.
What is meant by the “Moon tide” and the “sun tide.”
Moon Tide: Excess gravitational force on the moon facing side of the earth, together with excess centrifugal force on the opposite side of the eath distorts earths water envelope to produce a symmetric bulge, with its crest maximum, or high tide, along the line connecting the centers of earth and moon depression or a trough or a low tide is produced at 90° to the bulge.
Sun Tide; Due to the earth’s large distance from the sun, the sun’s tidal effect is only 46% of that of the moon. Since a point on earth rotates once every 24 hours with respect to the sun, instead of one every 24:50 hours with respect to the moon, the larger moon tide wave advance everyday an extra 12° east relative to the sun’s tidal wave.
Is the “tide wave” a deep water wave or a shallow water wave?
It is a shallow water wave.
What is a “tidal bore?” Give some examples of where they occur.
Along shallow coasts, in bays, and at river mouths, a rapidly moving-in, large amplitude wave breaks, forming a spilling wave. Its wave front appears as a wall of turbulence water called a tidal bore. The Amazon and the Seine have tidal bores, and the sand flats around Mont-Saint-Michael.
Explain how onshore and longshore currents transport material toward a beach.
A net landward water motion called the onshore current and its associated sediment transport called the onshore transport.

An along the beach water motion called the longshore current and its associated sediment transport called the longshore transport
Explain how “rip currents” transport material away from the beach.
In contrast to longshore currents, rip currents or rip tides move sediment offshore. These currents form perpendicular to the shoreline when water brought to shore by breakers returns seaward via depressions in the seafloor or through breaks in offshore bars. Rip currents are narrow and localized and can move with speed and force. They are the source of undertow, about which swimmers are often warned.
What visible signs could one tell that a rip current was present at a beach?
Signs that a rip current is present are very subtle and difficult for the average beachgoer to identify. Look for differences in the water color, water motion, incoming wave shape or breaking point compared to adjacent conditions. Look for any of these clues:
•Channel of churning, choppy water
•Area having a notable difference in water color
•Line of foam, seaweed, or debris moving steadily seaward
•Break in the incoming wave pattern
•One, all or none the clues may be visible.
Know some examples of “primary coasts” and “secondary coasts.”
Primary Coasts: fjords, moraines, drowned river valleys (ria coast), river deltas, alluvial plain, dune coast

Secondary Coasts: Clifted coast erosion, sea stacks, sand bars, barrier islands, sand spits, and hooks.
What is an “estuary?”
Semi-isolated portion of the ocean that is diluted by freshwater drainage from land
Know the four types of estuaries discusses in class.
1. Salt-wedge estuary- typically a river mouth, in it sea water forms a sharply defined wedge, moving under the fresh water with the tides; its circulation and mixing called entrainment, is controlled by the river discharged rate (river flow must be relatively fast)
2. Well-mixed estuary- typically a shallow, wide river mouth, it has a net seaward flow at all depths, due to the strong tidal mixing and weak river flow; salinity is uniformed with depth but decreases inward along the estuary.
3. Partially-mixed estuary has strong turbulence (mixing) seaward surface flow of mixed fresh and seawater, and an inflow of seawater at depth.
4. Fjord-type estuary- is a deep estuary in which fresh water moves out at the surface, but there is little tidal mixing or inflow at depth.
What is a “Red Tide?”
Single-celled organisms (algae) that discolor seawater
Why was the name changed to “Harmful Algal Bloom (HAB)?”
Formally known as “red tides” but they have nothing to so with tides and some species of algae may bloom and not color the water red. Also some species of algae may bloom and color the water, but are not harmful to humans and other organisms.
Where do red tides typically occur every year?
Red tides have occurred off the west cost of Florida for over 160 years and occur almost every year in the Gulf of Mexico usually in the late summer of early autumn.