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77 terms

Physical Oceanography (Currents, Waves, & Tides)

Use this to help you review some of the terms and defitions associated with physical oceanography.
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Surface Currents
These transfer heat from tropical to polar regions, distribute nutrients, scatter organisms and influence weather and climate.
Wind
Surface currents are powered by the sun and ______________
Gyre
Circular flow pattern of water caused by deflection of water by continents and the ocean basin.
Equator
Due to the warmth of the water, the molecules are slightly expanded in this region.
Poles
Due to the cold temperature of the water, the water molecules are slightly closer together in this region.
Countercurrents
Currents flowing on surface in opposite direction to main currents.
Undercurrents
Countercurrents beneath surface currents. Can influence conditions at the ocean surface.
Eastern
There are five of these boundary currents. They carry cold water towards the equator.
Eastern
These boundary currents are shallow and broad with boundaries that are not well defined.
Eastern
Eddies do not tend to form in these boundary currents.
Transverse
In these boundary currents, the flow is from East to West or West to East. They link eastern and western boundary currents.
Transverse
The West Wind Drift is an example of this type of boundary current.
Western
These are the fastest flowing boundary currents.
Western
These boundary currents move warm water from the equator towards the poles.
Western
The Gulf Stream is an example of this type of boundary current.
Sverdrop
This measurement of volume of water flow is equal to 1 million metres cubed per second.
Western
These boundary currents are narrow and deep and have sharp boundaries. Eddies can form.
Ekman Spiral
surface winds drive surface currents, and each layer of water drags the layer below, but the Coriolis Force changes each layer's direction slightly to make a spiral effect
Geostrophic Gyres
Gyres in balance between gravity and the Coriolis Effect.
Clockwise
Which direction do gyres flow in the Northern hemisphere?
Counterclockwise
Which direction do gyres flow in the Southern hemisphere?
Energy
Waves transmit _______________.
Long
Waves with ___________ wavelengths move the fastest.
Capillary waves
The slowest moving waves.
Tides
The fastest moving waves
Tsunami
Wave generated as a result of a seismic event.
Wave Frequency
Number of waves passing a fixed point per second.
Orbit
Nearly friction free transfer of energy from molecule to molecule in a circular path.
Progressive Wave
A wave of moving energy in which the wave form moves in one direction along the surface of the transmission medium.
Wave crest
highest part of a progresive wave
Wave trough
lowest part of a progressive trough
Wavelength
Horizontal distance between two consecutive wave crests or wave troughs
Wave Height
Vertical distance between a wave crest and an adjacent wave trough
Deep
These waves move through water greater than 1/2 their wavelength.
Shallow
These waves move through water shallower than 1/20 their wavelength
Transitional
These waves travel though water deeper than 1/20 but shallower than 1/2 their wavelength
Capillary
These waves are the first to form when the wind blows.
Capillary
Waves with a tiny wavelength less than 1.73cm. The restoring force is surface tension.
Gravity
These waves have a wavelength greater than 1.73cm. The restoring force is gravity and momentum. Wind waves are one example of these waves.
Wind
These waves tend to be less than 3m high, and have wavelengths between 60 - 150m in the ocean.
Swell
mature wind waves of one wavelength that form orderly undulations of the ocean surface
Wave Trains
Progessing groups of swell with the same origin and wave length are known as this.
Fetch
Uninterupted distance over which the wind blows without significant change in direction.
Wind Strength
The length of time the wind blows, the fetch and this are three factors that affect wind wave development.
1:7
Maximum ratio of wave height to wavelength seen in the open ocean. Also known as wave steepness.
Break
Waves with a ratio greater than 1:7 will do this.
Destructive interference
The subtraction of wave energy as waves meet producing smaller waves.
Constructive interference
The addition of wave energy as waves meet producing larger waves.
Surf beat
A result of constructive and destructive interference that is seen on shore when waves do not all appear with a uniform size. Some are larger, some are smaller.
Rogue Wave
A single wave crest much higher than usual caused by constructive interference.
Semidiurnal
This type of tidal cycle is found commonly in the Atlantic and Pacific Oceans.
Diuranal
This type of tidal cycle is found commonly in the Gulf of Mexico.
Plunging Wave
A breaking wave in which the upper section topples forward and away from the bottom, forming an air-filled tube.
Spilling Wave
A breaking wave whose crest slides down the face of the wave.
Surging Wave
A wave that surges ashore without breaking.
Wave refraction
Slowing and bending of progressive waves in shallow water.
Wave diffraction
Bending of waves around obstacles.
Wave reflection
The reflection of progressive waves by a vertical barrier. Reflection occurs with little loss of energy.
Standing Wave
a wave in which water oscillates without causing progressive wave forward movement. there is no net transmission of energy in a standing wave
Tides
the regular rise and fall of the ocean's surface influenced by the moon's gravity pulling on earth
Lunar Tide
Tide caused by gravitational and inertial interaction of the moon and Earth.
Lunar Day
24 hours 50 mins
Pytheas
Greek astronomer and navigator who first wrote about the connection between moon and the height of the tide.
High Tides
High water position corresponding to a tidal crest
Low Tides
Low water position corresponding to a tidal trough
Spring
These tides occur when the earth, moon and sun are in a straight line.
Neap
These tides occur when the earth, moon and sun are at right angles.
Solar Tides
caused by the gravitational and inertial interaction of the sun and earth
Neap
These tides result in little variation in the height of tides.
Spring
These tides are a time of greatest variation between high and low tides.
Amphidromic Point
A "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate. About a dozen amphidromic points exist in the world ocean. Sometimes called a node.
Tidal Bore
A high, often breaking wave generated by a tide crest that advances rapidly up an estuary or river.
Tidal Range
is the difference in height between successive high and low tides
Tidal Datum
The reference level (0.0) from which tidal height is measured.
Slack Water
a time of no current, occurs at high and low tides when current change direction
Flood Current
water rushing into an enclosed area because of the rise in sea level as a tide crest approaches
Ebb Current
Water rushing out of an enclosed harbor or bay because of the fall in sea level as a tide trough approaches.