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105 Cards in this Set
- Front
- Back
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Surface current
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currents that are wind driven
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deep currents
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currents that are density driven and indirectly by wind
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tracers
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such as radioactive elements, can be used to track large-scale movement of deep ocean water
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gyres
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subtropical circular ocean current patern; wind driven
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equatorial currents
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currents that are driven by the trade winds, and flow from east to west
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western boundary currents
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currents that form where equatorial currents encounter the continental margin on the western side of the ocean basin; carry warm water to high latitudes
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eastern boundary currents
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currents that carry cool water from high latitudes to the south
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northern boundary currents
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currents in the northern hemisphere subtropical gyres
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southern boundary currents
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currents in the southern hemisphere subtropical gyres
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equatorial counter currents
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currents that flow from west to east to compensate for the flow of the equatorial currents
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subpolar gyres
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gyres that develop in high latitudes from a combination of surface winds from the westerlies and polar easterlies
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Ekman spiral
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Surface currents flow at a 45 degree angle from wind due to the Coriolis force
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Ekman transport
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The average movement of these currents is 90 degrees to the right of the direction of surface wind
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geostrophic flow
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results when the combination of gravity and Coriolis force cause water to flow in concentric paths around the center of the gyre
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western intensification
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Gyres have centers that are offset to the west. This causes western boundary currents to be faster, narrower, and deeper than eastern boundary currents
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upwelling
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the vertical movement of cold, often nutrient-rich water to the surface
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downwelling
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the movement of water from the surface to depth. These zones are important because their nutrient-rich waters may host abundant biological productivity
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East Wind Drift
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The coastal current driven in a westerly direction by the polar easterly winds blowing off Antarctica
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Sverdrups
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Large flows in the oceans are measured in a unit called ?; with 1 Sv = 1 million cubic meters per second!
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Sargasso Sea
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an area of weak currents near the center of the North Atlantic gyre
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eddies
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Bends or meanders in the current close on themselves and create large spinning masses of water
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monsoons
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circulation is altered by strong seasonal winds
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Peru current
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the cold eastern boundary current of the south pacific subtropical gyre
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Pacific warm pool
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As currents push water west across the Pacific they warm, generating a zone of warm surface temps known as ...
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Walker Circulation
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The sharp contrast between the warm waters of the western Pacific and the cool waters of the Peru current leads to the development of high and low pressure systems that drive...
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El Nino
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Every few years coastal winds weaken and the warm pool pushes east towards Peru, bringing heavy rain and poor fishing. At the same time, high pressure develops in the western Pacific, leading to dry conditions
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La Nina
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some years coastal trade winds are very strong, intensifying upwelling in the Peru current as well as Walker Circulation
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ENSO (El Nino-Southern Oscillation)
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This cycle of ocean-atmosphere interactions is formally known as ...
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interannual cycles
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they occur on an irregular basis every 2 to 10 years, with 3-7 years being the most common interval, with typical event duration between 12 and 18 months.
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North Atlantic Oscillation (NAO)
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influences weather and currents in North America and Europe on decadal cycles.
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Pacific Decadal Oscillation (PDO)
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a 20-30 year cycle that was first linked to variations in the salmon fishery and is now thought to influence northern Pacific climates, and may interact with ENSO cycles to produce very strong climate variations.
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thermohaline circulation
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oceanographers can now document the existence of deep water currents. These currents are driven by differences in temperature and density of seawater
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North Atlantic Deep Water
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a deep-water mass that forms primarily at the surface of the norwegian sea and moves south along the floor of the North Atlantic Ocean
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Antarctic Bottom Water
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a water mass that forms in the weddell sea, sinks to the ocean floor, and spreads across the bottom of all oceans.
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Tsunami
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A seismic sea wave. A long-period gravity wave generated by a submarine earthquake or volcanic event. Not noticeable on the open ocean but builds up to great heights in shallow water
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Surface waves
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Most common waves - wind driven
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internal waves
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develop within the ocean between water layers of contrasting density. only affect submarines
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splash waves
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may develop from coastal landslides or iceberg calving.
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waveforms
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The three principle types of waves
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longitudinal waves
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Waves with a push-pull motion in the same direction that the wave travels. Travels through all forms of matter
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transverse waves
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energy travels perpendicular to the wave direction - only travel through solides
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orbital waves
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energy travels in circular motions along the wave - most common with density - air/water
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crest
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high part of wave
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trough
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low part of wave
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still water level
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half way between the crest and trough
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wave height (H)
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the vertical distance between crest and trough
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wave length (L)
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the horizontal distance between wave crests
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wave steepness
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The ratio of wave height to wave length
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wave period (T)
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the time it takes for one wavelength to pass a fixed point
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wave frequency
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the number of wave crests that pass a fixed location in a defined period of time
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circular orbital motion
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Waveforms can travel great distances, but the water in the wave does not travel with it. Instead, water travels in a circle with the wave, passing the energy along
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wave drift
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particles don’t return to their exact starting point because motion in the trough is slower than motion of the crest
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wave base
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The depth at which circular orbital movement becomes negligible
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deep water waves
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are waves that do not “feel” the sea floor because water depths are greater than or equal to (L/2). All wind-driven waves on open water
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celerity (C)
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The speed of waves travel - measures the speed of wavform - Wavelength/Period
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shallow water waves
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Waves with water depth less than or equal to 1/20 of wavelength (i.e. L/20). These waves “feel” the ocean floor.
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transitional waves
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develop in areas where water depth is between L/20 and L/2
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capillary waves
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When wind blows on the ocean surface, the first waves to develop are small ripples (L < 1.74 cm)
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gravity waves
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If the wind continues to blow, wavelength may begin to exceed 1.74 cm. These larger waves are known as ...
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fetch
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the distance over which the wind blows in one direction
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fully developed sea
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the limit of wave size based on wind speed, fetch, time, and wave steepness.
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swells
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Once waves leave the area where they formed, their steepness decreases and wavelength increases
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wave trains
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Swells and waves often travel in groups known as...
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interference patterns
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When waves of different heights and lengths meet, their energy is combined into...
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constructive interference
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When wave trains have the same heights and lengths and meet in phase (matching crest-to-crest and trough-to-trough), wave length stays the same but wave height becomes the sum of the two wave trains.
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destructive interference
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When wave trains have the same heights and lengths and meet out of phase (matching crest-to-trough and trough-to-crest), the waves will cancel each other out and disappear.
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mixed interference
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When wave trains of differing heights and lengths meet, an alternating pattern of smaller and larger waves develop.
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rogue waves
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Interference and interaction between waves and currents can produce very large, solitary waves that seem to come from nowhere
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shoaling
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When waves transition from deep water to shallow water, they experience changes collectively known as ...
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surf zone
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Waves break when their steepness reaches the 1/7 ratio. The area where waves break is known as...
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breakers
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Waves breaking in the surf zone are also referred to as ...
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spilling breakers
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develop in low slope coastal areas. They last for a long time but have lower energy.
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plunging breakers
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have curling crests that form an air pocket. They develop in moderately sloping beaches and are the classic surfer’s wave.
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surging breakers
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form surging walls of water and break quickly. They form in areas where the sea floor shallows abruptly and are the least desirable surfing wave.
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wave refraction
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When waves break at an angle to the shore, the part of the wave that feels bottom first slows down, causing the wave crest to bend. This bending of wave crests is known as...
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orthogonal lines
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drawn perpendicular to the wave crest, and show how the energy is distributed through refraction.
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point breaks
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the waves that break at a headland
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wave reflection
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occurs when a wave is “bounced” off of a barrier like a seawall or jetty while retaining much of its energy.
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Barycenter
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the common center of mass between the Earth and Moon
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gravity
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the attraction between particles of mass in the universe
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zenith
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point of greatest gravitational attraction
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nadir
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point of weakest gravitational attraction
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centripetal force
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a center-seeking force that tends to make rotating bodies move toward the center of rotation
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tidal bulges
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the theoretical mound of water found on both sides of earth caused by the relative positions of the moon and the sun
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full moon
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occurs when the Moon is directly opposite the Sun, behind Earth.
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new moon
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occurs when the Moon is directly opposite and in-between the Sun and Earth.
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1st quarter moon and 3rd quarter moon
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occur when the Moon is at right angles to the Earth and Sun.
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tidal range
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difference between low and high tide
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spring tides
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When the solar tide and the lunar tide are in alignment, tides have their strongest influence with the highest tidal range
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neap tides
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When the sun and moon are at right angles, tides have a lower range
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Declination
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The Earth’s axis is tilted 23.5 degrees from vertical, and the Moon’s orbit about the Earth is tilted 5 degrees relative to the Earth’s orbit about the Sun (ecliptic).
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eccentricity
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Both the orbit of the Moon around the Earth and the orbit of the Earth around the Sun are elliptical, i.e. oval-shaped.
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perigee
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closest to the Earth
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proxigean tides
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a tidal condition of extremely large tidal range that occurs when spring tides coincide with perigee. AKA "closest of the close moon" tides
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perihelion
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The Earth is closest to the Sun
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tidal cells
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Because tidal bulges are shallow water waves, their passage is slowed by friction with the ocean floor. As a result, tidal bulges break into units known as...
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cotidal lines
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a line connecting points where high tide occurs simutaneously
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amphidromic points
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a nodal or "no-tide" point in the ocean or sea around which the drest of the tide wave rotates during one tidal period
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diurnal tidal patterns
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have a single low and high tide each day, and are common in shallower parts of the oceans like the Gulf of Mexico.
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semidiurnal tidal patterns
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have two high and two low tides every day and most closely resemble idealized tidal patterns. They are common on the Atlantic coast.
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mixed tidal patterns
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have elements of both semidiurnal and diurnal tidal patterns. Mixed patterns typically have high and low tides of differing heights during the day.
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flood currents
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form during the rising of the tide.
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ebb currents
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form during falling tides.
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tidal bores
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are waves that form when flood currents interact with river water flowing the opposite direction to form a wave.
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The Maelstrom
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whirlpool
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