Study Guide Questions Answers PDF

Preview

Summary

Notes from UAlbany class...

Description

1 Study Guide Questions October 25 1) What sets surface ocean currents in motion? Surface currents in the ocean are set in motion by prevailing large-scale atmospheric surface circulation (winds). 2)

Why is the Coriolis effect more effective in the oceans than in the atmosphere? The Coriolis effect is more effective in the oceans than in the atmosphere because the density of water is 1000 times the density of air so therefore the ocean currents are much slower than in winds.

3)

What is a “gyre,” where are they located and what direction do they rotate? A gyre is a large circular motion current system, they are located at 30 deg latitude and go between the trade winds and the westerlies and are bounded by landmasses from the east and the west, NH gyres rotate clockwise and SH gyres rotate counterclockwise.

4)

What is the “Ekman Spiral?” Describe “Ekman Transport” in the oceans. The Ekman Spiral is waters viscosity (small internal friction) which causes water in the layer just below the surface to move more slowly and therefore be deflected more by the coriolis effect to the right in the NH and to the left in the SH than in the surface layer (top layer). Ekman Transport in the oceans is the depth averaged flow in the Ekman spiral is at 90 deg to the right in the NH and 90 deg to the left in the SH.

5)

What is meant by “geostrophic flow” around a gyre? A geostrophic flow around a gyre refers to when a balance between the upper portion of the water in the gyre to converge towards its center to form a dome is reached and the flow around the gyre exactly follows the water elevation contours.

6)

What are the primary ocean currents in the Atlantic, Pacific and Indian Oceans? The primary ocean current in the Atlantic Ocean is the Gulf Stream, in the Pacific Ocean it’s the California current, and in the Indian Ocean it’s the West Australia current.

7)

Which are the primary “warm” and “cold” currents in the Atlantic? The primary warm and cold currents in the Atlantic are the Florida current, Gulf stream, and Norwegian current (warm) and the Labrador current (cold).

8)

Which are the primary “warm” and “cold” currents in the Pacific? The primary warm and cold currents in the Pacific are the Kuroshio current and the Equatorial Countercurrent currend (warm) and the California current, Alaska current, Humbolt/Peru current (cold).

2 October 28 1) How do current speeds compare to that of the wind? Current speeds are 1/100 that of winds. 2)

3)

Explain the “western intensification” of currents. The western intensification of currents is an increase of coriolis deflection with latitude, changing strength and direction of the wind with latitude, and friction between landmasses and currents. What are “eddies” and how are they formed? Eddies are distinct packets of water moving in a circular clockwise/counterclockwise motion. They are formed when a fast moving horizontal current develops waves along its boundaries, which are called meanders that break off as circular whirlpools from the parent current.

4)

What is another name for “eddies?” Another name for eddies can be called abyssal storms.

5)

Where does ocean surface “convergence” occur? Surface convergence occurs when in a downwelling region, where surface water moves in to replace denser, sinking water, where surface currents collide, and near coasts when winds force currents against landmasses, causing downwelling.

6)

Where does ocean surface “divergence” occur? Surface divergence occurs when in an upwelling region, where surface water is forced away by the lighter rising water, when surface currents separate, and near coasts, when winds blow surface water away from landmasses, causing upwelling.

7)

Where are the five permanent convergence zones (CZ)? The five permanent convergence zones are at the Equatorial tropical, two at the subtropical at 35 deg N & S and two polar at 50 deg N & S.

8)

Where are the three permanent divergence zones (DZ)? The three permanent divergence zones are at the polar/Antartica at 60 deg to 70 deg S, and two tropical north and south of the equator.

November 1 1) What are the biological benefits to upwelling and downwelling? The biological benefits to upwelling is that it brings nutrients to the ocean surface, which cause excellent fishing areas and downwellings bring oxygen down in the waters. 2) What are “windrows?” Windrows are a series of parallel “rows” of debris lining up in the direction of the wind, they mark the convergence zones of shallow, wind driven helixes called Landmuir cells.

3 3) Give examples of “aperiodic” and “periodic” mechanisms that are a part of Earth’s dynamic changes and climate variability. Examples of aperiodic are large-scale volcanic eruptions, plate shifts, and collisions with asteroids, and periodic are milankovick cycles of variations solar radiation on earth, which is received at high latitudes during the summer. 4) What are the three “Milankovich Cycles?” Why are they important? The three Milankovich cycles are eccentricity orbit (a 100,000 year cycle from nearly circular to slightly elliptical), an axial tilt (a 41,000 year cycle of changes of tilt in earth’s axis of rotation), and the precession of equinoxes (wobble) ( 23,000 AND 19,000 year double cycle from pointing towards Polaris to pointing toward Vega). 5) Describe the combined wind-driven and thermohaline flow of ocean water around the planet (“global oceanic conveyor belt”). The combined wind-driven and thermohaline flow of ocean water around the planet flows from ocean to ocean through the basins. 6) Where are the major ocean basins most connected to one another? The major ocean basins are most connected to one another one around Antarctica. 7) How long does it take surface water to cross an ocean basin? It takes surface water 5 years to cross an ocean basin. 8) How long does it take deep water to cross an ocean basin? It takes deep water 1000 years to cross an ocean basin. 9) What likely happened to the North Atlantic Circulation during the last mini-ice age and why? The North Atlantic Circulation had a shut down of circulation caused by a sudden change in position of meltdown from the receding North American glacial ice sheet, which caused a mini-ice age. 10) Where is the “Sargasso Sea” and why is it a “mysterious” place in the world? The Sargasso Sea is located in the center of the North Atlantic and it is a mysterious pace in the world because there are seas in the center of other gyres especially in the Sargasso Sea. It is located in the heart of the Bermuda Triangle. 11) What is so “unique” about the “Sargasso Sea?” The Sargasso Sea is unique because its currents are largely immobile, but it rotates slightly clockwise and can shift position as the surrounding stronger currents change with storms and the seasons. 12)What is “St. Elmo’s Fire?” St. Elmo’s fire is a phenomenon sometimes seen while at sea during thunderstorms where bright blue or violet plasma discharges (a glow like fire) coming off various masts.

4 November 4 1) List the three primary “generating forces” of ocean waves. The three primary generating forces of the ocean waves are the wavelengths (distance between two crests), period (time between two crests), and the node (wave elevation is undisturbed level). 2) What is the primary “restoring force” of a fully developed large ocean wave? The primary restoring force of a fully developed large ocean wave is Earth’s gravity, which takes over from surface tension to restore larger gravity waves generated by stronger winds. 3) Become familiar with the terms describing the “characteristics of a wave”, especially wavelength (L), period (T) and wave speed (C). 4) To what depth do the orbital motion of water particles of a deep water wave extend? The depth that the orbital motion of water particles of a deep water wave extend is at one half the wavelength of the wave. 5) Define “wave speed” in terms of its wavelength and period. Wave speed (C) = Wavelength (L) / Period (T) 6) Define a “deep water wave?” What generates them? What restores them? A deep-water wave is waves in which occurs in water whose depth exceeds one half the wavelength of the wave. Deep water waves are generated by wind and they are restored by gravity. 7) Which move faster, longer deep-water waves or shorter deep-water wave? Longer deep-water waves move faster than shorter deep-water waves. 8) Explain the difference between storm generated “forced waves” and “free waves.” Forced waves are waves that are caused by prevailing winds or winds that are circulating around a moving ocean storm center and free waves are waves that are sufficiently far from the storm. 9) What does the “dispersion” of storm generated waves cause the waves to do? The dispersion of storm generated waves cause the waves to sort out so that the longer waves move out faster tending to group as wave trains or packets of waves with similar wavelength and wave periods. 10) What are “wave trains (wave packets)?” Wave trains are sets of waves with similar wavelength and wave periods that carry the wave energy.

5 11) What is the relationship between “group speed” (packet speed), V, and individual “wave speed,” C? The relationship between group speed (V) and wave speed (C) is that the group speed is about half that of the individual wave speed. V=C/2 12) What are “swells?” Swells are the long slow regularly shaped wave trains that remain and continue to travel long distances away from the storm. November 6 1) What happens when waves are “in phase” and “out of phase?” When waves are in phase the crest of one wave coincides with the crest of another wave so that their wave heights are added together to create a higher wave. When waves are out of phase the crest of one wave coincides with the trough of another wave so that their wave heights cancel out and produce a smaller wave or no wave at all. 2) “Wave height” is dependent on what three factors? Wave height is dependent on wind speed, wind duration, and fetch (the distance over which steady wind blows). 3) What is meant by “significant wave height?” Significant wave height is when a wave whose height ranks 34th among 100 waves arranged in order of ascending height. 4) “Wave energy” is directly proportional to what? Wave energy is directly proportional to wave height. 5) Define “wave steepness.” What steepness ratio will cause a “wave to break?” Wave steepness is the ratio of wave height to wavelength (S=H/L). The steepness ratio that causes a wave to break is 1:7 which makes the wave break and the short waves break more easily than the long waves. 6) Define a “shallow water wave.” A shallow water wave is where water depth decreases to less than L/20. 7) What happens to the water particle motion, as the waves “feel the bottom?” The water particle motion becomes more elliptical as the waves feel the bottom. 8) How are “wave rays” refracted along a regular coastline? The wave rays are refracted along a regular coastline when their wave rays draw perpendicular to the crests and bend towards the shore. 9) How are “wave rays” refracted along an irregular coastline? The wave rays are refracted along an irregular coastline at more vertical, deeper shore barriers, such as cliffs, steep beaches, or bulkheads.

6

10)How does the reflection of “wave rays” cause “choppy seas?” The reflection of wave rays cause choppy seas are caused by combinations of incoming and outgoing waves which cause interference patterns. 11)When do “wave rays” undergo diffraction? What causes the “diffraction?” Wave rays undergo diffraction when incoming waves pass through narrow openings in breakwater barriers or move past barriers. Diffraction is caused by a spread or divergence of wave energy due to a decrease in wave height after the wave crest passes the barrier. 12)How did “ancient mariners” navigate between islands? Ancient mariners navigated between islands by watching the reflection and diffraction of wave patterns in the ocean. November 8 1) What is the “Surf Zone?” The surf zone is a shallow coastal region in which waves slow down rapidly, quickly steepen and break, and dissipate as turbulence and spray. 2)

Explain the difference in breaking waves between “plungers” and “spillers.” The difference in breaking waves between plungers and spillers is that plungers form on narrow, steep beach slopes, when a curling crest rapidly outruns the rest of the wave, quickly losing energy and spilling over, and spillers form over wider, flatter beaches, as waves gradually move up the shallow bottom.

3)

Which type of breaking waves do surfers prefer for a thrilling, adrenaline pumping ride? The type of breaking waves that surfers prefer for a thrilling, adrenaline pumping ride are the plungers.

4)

What is a “rip current”? A rip current is where the water is returned back to the sea through the surf zone, which is some distance away from the onshore currents.

5)

How is a swimmer advised to escape from a dangerous “rip current”? A swimmer is advised to escape from a dangerous rip current by swimming parallel to the beach.

6)

What are “internal waves?” How are they generated? Internal waves are waves, which form between water layers of different densities, usually at the pycnocline, which separates the shallow mixed surface layer from the denser layer underneath. They are generated by low pressure of a storm, changes of ocean currents with depth, and currents moving over the sea bottom.

7

7)

What are “standing waves?” How are they generated? Standing waves are generated when a progressive wave reflects back upon itself, the reflected motion cancels the forward motion.

8)

What is the difference between single-node and two-node standing waves? The difference between single-node and two-node standing waves is that single-node waves are in a closed basin, which contains half the wave, and two-node standing waves are in a closed basin, which contains a full wave. What is a “seiche?” A seiche is a single node oscillation.

9)

10) What is a “mega-tsunami” and how does it differ from a “tsunami?” A mega-tsunami is a very large “tsunami-like” wave that is caused by an explosive volcanic event, a very large meteor, asteroid or comet impact, or very large landslide into a body of water that can’t disperse in all directions. November 11 1) What are the four primary causes of a tsunami? The four primary causes of a tsunami are earthquakes, volcanic eruptions, landslides, and meteor, asteroid, or comet impact. 2)

What is a typical wavelength, wave height, period and speed of a tsunami? A typical wavelength (L) of a tsunami is 100-840 km, period (T) is 10-60 minutes, and speed (C) is 200 m/sec.

3) Is a tsunami a “deep water wave” or a “shallow water wave?” Explain. A tsunami is a shallow water wave because the average ocean depth is 4 km. 3)

How can a tsunami wave pass relatively unnoticed under a ship at sea? A tsunami wave passes relatively unnoticed under a ship at sea because the steepness of a tsunami is extremely low and when combined with a long period.

4)

What happens to the tsunami wave as it approaches a coast? When a tsunami wave approaches a coast the wave slows down and shortens.

5)

Why does the water often recede out to sea minutes before a tsunami strikes? The water often recedes out to sea minutes before a tsunami strikes because the leading edge of the trough is ahead of the bottom of the wave.

6)

How do animals know to flee to higher ground before a tsunami strikes? Animals know to flee to higher ground before a tsunami strikes because they have an ability to sense subsonic Rayleigh waves from an earthquake.

8 7) Where do tsunami typically occur most often? Tsunamis typically occur most often in tectonically active regions, mainly in the Pacific and Indian Ocean. November 13 1) What is a “rogue wave?” A rouge wave is a wave that comes out of the blue, which creates holes in the sea before crashing down on ships in the open sea, sinking many ships. 2) List the major characteristics of rogue waves. The major characteristics of rouge waves are that they are more than 3-4 times the size of surrounding waves, wavelengths of 1 km, deep-water waves, associated with steep forward face preceded by a very deep trough, wall of water, and are unpredictable. 3) Why are rogue waves so devastating to ships at sea? Rouge waves are so devastating to ships at sea because they have varying speeds they are unexpected, and are huge. 4) What are the four probable causes of rogue waves? The four probable causes of rouge waves are large storms at sea, focusing of wave energy; normal part of the wave height spectrum, and quantum physics Schrödinger equations. 5) What “quantum physics” equations explain the non-linear nature of rogue waves? The quantum physics equations that explain the non-linear nature of rouge waves are the Schrodinger equations. November 15 1) Know the difference between diurnal, semi-diurnal and mixed tides? Diurnal tides have one high tide and one low tide per day, semi-diurnal tides have two high tides and two low tides per day of equal water level, and mixed tides have two high tides and two low tides of unequal water levels. 2) What is a “flood tide?” What is an “ebb tide?” What is “slack water?” A flood tide is a rising tide, an ebb tide is a falling tide, slack water is when a tide turns around (changing tides). 3) Qualitatively explain Newton’s Law of Universal Gravitation Newton’s Law of Universal gravitation is where the force of gravitational attraction between any two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. 4) What two forces keep the Earth-Moon system in balance? The two forces that keep the earth-moon system in balance are the gravitational force of attraction and the centrifugal force of the moon’s orbital motion.

9

5) What is “Equilibrium Tidal Theory?” The equilibrium tidal theory examines tides as idealized water waves on an Earth, covered by a uniform layer of water. It explains tides as a balance between gravitational and centrifugal forces. 6) What is meant by the “Moon tide” and the “Sun Tide?” The moon tide refers to the excess gravitational force on the moon-facing side of the earth, the sun tide is because of earth’s large distance from the sun, so therefore the sun’s tidal effect is only 46% of that of the moon. 7) Why does the Moon rise about 50 minutes later each day? (Hint: lunar tidal day) The moon rises about 50 minutes later each day because the time required to complete the 372 deg is 24 hours and 50 minutes. 8) What is a “tidal wave?” Is it a deep-water wave or a shallow water wave? ****A tidal wave an effect of a semi-diurnal moon tidal distortion of the water envelope. It is a shallow water wave. 9) What are the names of the tides associated with each phase of the moon? **New moon is when the earth, moon, and sun are aligned so it produces tides of maximum height and deptession called spring tides. **First quarter tides are when the moon is at 90 deg to the earth-sun that minimizes the tidal range, which is called neap tides. **A full moon tide is when the three bodies are aligned producing another spring tides. **Third (last) quarter tides is when the moon is at 270 deg to the earth-sun line, and a neap tide occurs again. 10) Which has more effect on the tides, the sun or the moon? Explain. The moon has a bigger effect on the tides because it has a bigger gravitational pull. 11) What is a “tidal bore?” Give some examples of where they occur. A tidal bore is a wave front that appears as a wall of turbulent water that produces an abrupt change in water level. They occur in the Bay of F...