GLOSSARY

Albedo:
the ability of a planet to reflect light; whiteness
Angle of Incidence:
the angle between a wave front (usually an electromagnetic wave) or a wave ray and the plane of an interface that it meets; the angle of approach; important in refraction
Atoll:
a ring shaped coral reef that grows upward from a submerged volcanic peak and encloses a lagoon; may support low-lying islands composed of coral debris
Barrier Reef:
a coral reef that parallels the shore but is separated from the landmass by open water
Beacon:
a radio transmitter that emits a signal as a warning or guide
Bergy Bits:
icebergs that have broken up into pieces too small to be considered a threat; they are officially no longer considered to be an iceberg
Boundary Currents:
A fast geostrophic currents found close to the coast on the west side of a gyre. The Gulf Stream is an example of a western boundary current
Buoy:
a floating object anchored to the bottom or attached to another object; used as a navigational aid or surface marker
Calving:
the process of icebergs breaking off from glaciers
Carbon Dioxide:
a gas that is necessary to the functioning of most life forms
Castle Berg:
an icebergs formed in the Arctic regions from mountain glaciers fed by the Greenland ice sheets; they are high and narrow, with above-water shapes resembling towers
Coral(s):
the skeletal remains secreted by small marine polyps; their unique form makes them easily mistaken for plants
Coral Polyp:
a tiny animal that looks like an upside-down jellyfish; a benthic cnidarian that can exist individualy or in colonies and may secrete external skeletons of calcium carbonate
Coral Reef:
formed when hundreds of hard coral colonies grow next to and on top of each other; a mainly calcareous reef composed substantially of coral, coraline algae, and sand; present only in waters where the minimum average monthly tempurature is 18 degrees C or higher
Coriolis Effect:
an apparent deflection of a freely moving object caused by the Earth's rotation
Crest:
for a wave, the portion that is displaced above the still water line; often used to refer to the highest point of the wave (or other topograpic feature) only
Current:
a steady horizontal movement of water or air in a definite direction; ocean currents flow in complex patterns affected by wind, the water's salinity and heat content, bottom topography, and the Earth's rotation
Deep Ocean Circulation:
the slow circulation of water at great depths is driven by density differences rather than by wind energy
Deep-Water Waves:
an ocean wave that is traveling in water depth greater than one-half its wavelength
Density:
the average mass per unit volume; a measure of how much matter is squeezed into a given space; the more closely packed the molecules, the higher the density of the material. Density in the ocean is determined by salinity and temperature
Doppler Shift:
the change in the tone of a sound caused by the sound source moving away or towards the listener
Downwelling:
the vertical movement of a fluid downward due to density differences or where two fluid masses converge, displacing fliud downward. In the ocean, it often refers to where Ekman transport causes surface waters to converge or impinge on the coast, displacing surface waters to converge or impinge on the coast, displacing surface water downward thickening the surface layer
Eccentricities:
not the customary or ordinary behavior; unconventional movements or conduct; comes from eccentric, which means not exactly circular in shape or motion
Eddies:
circular movements of water
Ekman Layer:
the thin horizontal layer of water riding on top of the ocean that is affected by wind
Ekman Spiral:
Ekman transport combined with the Coriolis force cause each layer of water to change angle slightly creating a spiraling affect in the water. The spiraling is clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere
Ekman Transport:
process by which each layer of water in the ocean drags with it the layer beneath, thus the movement of each layer of water is affected by the movement of the layer above. Each successive layer feels the force of the surface layer a little less, sort of like the way words get jumbled in a game of telephone little by little as they pass from player to player
El Niño:
an episodic movement of warm surface water south along the coast of Peru associated with the cessation of upwelling in this region
El Niño Southern Oscillation (ENSO):
the complex episodic sequence of events in the oceans and atmosphere
Equi-Geopotential Surfaces:
see Geoid
Eulerian Velocity:
a measure of ocean currents which flow past a fixed position
Equinox:
either of the two times during a year when the sun crosses the celestial equator and the length of day and night are equal
Fetch:
the uninterrupted distance over which the wind blows (measured in the direction of the wind) without a significant change of direction
Fish Stocks:
the location where fishermen fish from
Fringing Reef:
a reef that is attached to the shore of an island or continent with no open water lagoon between the reef and the shore
Fully Developed Sea:
a sea produced by winds blowing steadily over hundreds of miles for several days
Geoid (Equi-geopotential surfaces):
the hypothetical surface of the Earth that coincides everywhere with the mean sea level
Geostrophic Flow:
refers to cyclonic fluid motions that are maintained as a result of a near balance between a gravity-induced horizonatal pressure gradient and the Coriolis effect
Geosynchronous Transfer Orbit (GTO):
are exactly 35,786 km above the equator; they move at exactly the same rate as Earth, so they seem to stay in the same spot in the sky when you look at them; used mostly for satellite TV
Glacial Ice:
the ice formed by the recrystalization of old compacted snow
Glaciers:
the large masses of ice that form on land by the recrystallization of old compacted snow; they flow from the area where they are formed downhill to an area where ice is removed by melting or calving (breaking off) into a water body
Global Conveyor Belt:
the major element or subsystem that carries heat in the ocean; it circulates warm water from tropical and subtropical regions towards the polar regions where it surrenders heat to the atmosphere, cools and sinks, and flows back towards the equator
Greenhouse Gas:
the gases in Earth's atmosphere that cause the greenhouse effect; include carbon dioxide, methane, and CFCs (chlorofluorocarbons)
Greenhouse Effect:
the trapping of heat in the atmosphere; incoming short-wavelength solar radiation penetrates the atmosphere, but the longer-wavelength outgoing radiation is absorbed by greenhouse gases and reradiated (sent back again) to Earth, causing a rise in temperature
Growler:
a berg that is less than 17 feet above sea level and less than 50 feet long
Gulf Stream:
carries warm gulf waters
Gyre:
a major circular moving body of water; it is created as boundary currents get deflected by winds and the Coriolis Effect. There are five gyres in our world ocean. Two each in the Pacific and the Atlantic Oceans and one in the Indian Ocean. They flow clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere
Hatchery:
a place where the eggs of fish are hatched
Heat Budget:
heat input and output "account" for Earth; the total solar energy received by Earth during a period of time is equal to the total heat lost from Earth--by reflection and radiation--into space through that same period of time
Heat Transport:
describes how the ocean currents carry and transport heat from ocean to ocean and from equator to poles to maintain Earth's temperature
Horizontal Pressure Gradient:
the force per unit area that causes molecules of water to move horizontally from regions of high pressure to regions of low pressure
Hydrosphere:
the gaseous, liquid and solid water of the Earth's upper crust, ocean and atmosphere; includes lakes, groundwater, snow, ice and water vapor
Ice Core:
a three-dimensional core or log of ice that is used for research
Ice Sheet:
a large tabular sheet of ice
Igneous rock:
created when melted rock, called magma, gets trapped in pockets deep inside the Earth. When the magma cools and hardens it is known as igneous rock. Igneous rock is also formed when lava from volcanoes cools and hardens. Lava is just magma that is no longer underground, but has come out through a volcano. Granite is an example of igneous rock. Igneous rock is very hard so water does not break it up very easily. That is why low salinity is associated with an igneous ocean floor.
Infrared:
refers to electromagnetic radiation with wavelengths greater than those of visible light and shorter than those of microwaves
Interglacial Period:
the time between glacial epochs
Kelp:
the various species of large brown algae
Labrador Current:
a cold ocean current flowing southward from Baffin Bay along the Labrador coast and turning east after joining the Gulf Stream
Lagoon:
a shallow body of water, seperated from the sea by sandbars and coral reefs
Lagrangian Velocity:
a measure of ocean currents which track a section of water as it flows
Larva:
the newly hatched, earliest stage of any of various animals that undergo metamorphosis
Low-Earth Orbit (LEO):
are about 800 to 1300 km above the ocean, and the orbit goes nearly over the poles
Mangrove:
a group of tropical plant species that grow in low marshy areas at latitudes below about 30 degrees; they have extensive root systems and produce much organic detritus to create a unique coastal environment for marine life
Meridional Overturning Circulation:
sinking and spreading of cold water
Migrate:
to change location periodically, usually seasonal
Mollusk:
marine invertebrate, from the phylum Mollusca
Mountain Valley Glaciers:
mountains composed of ice
Nansen Ocean Sampling Bottles:
cylindrical container that samples sea temperature and salinity
Original Sea State:
condition present before the onset of recent winds
Overfishing:
harvesting a fish species at a rate exceeding the maximum harvest that would still allow the population to be replaced by reproduction
Paleoclimate:
climates of the past
Perihelion:
the point nearest the sun in the orbit of a celestial body
Photosynthesis:
the process by which chlorophyll-containing cells in green plants convert incident light to chemical energy and synthesize organic compounds from inorganic compounds, accompanied by the release of oxygen
Planula:
the free-swimming, ciliated larva of a coelenterate
Polyp:
see Coral Polyp
Precession:
a complex motion excuted by a rotating body subjected to a torque tending to change its axis of rotation
Predation:
capture of prey as a means of sustaining life
Red Tide:
ocean waters colored by the dramatic increase of dinoflagellates that cause fish kills and paralytic shellfish poisoning
Salinity:
a measure of the quantity of dissolved salts in ocean water; defined in terms of the conductivity of a defined salt solution; has no units but is nearly equal to the weight in grams of dissolved salts per kilogram of seawater. The natural concentration of salts in water. This is influenced by the geologic formations underlying the area. Salinity is lower in areas underlain by igneous formations and higher in areas underlain by sedimentary formations. Higher salt concentrations are also more likely in arid regions where water evaporates leaving the same amount of salt in less water and thus increasing the salinity.
Satellite:
either a small celestial body orbiting a larger one, or a manmade object designed to orbit a celestial body
Sea-Surface Height:
the height the sea surface would be if there were no waves
Sedimentary Rock:
created when small particles of Earth and decomposed plant and animal life settle at the bottom of lakes, rivers and oceans and are compressed by the weight of the water until the bottom layers slowly turn into rock. Sandstone is an example of sedimentary rock. Sedimentary rock is very soft and easily flakes off, layer by layer. That is why high salinity is associated with a sedimentary ocean floor.
Shallow-Water Waves:
a wave whose wavelength is at least 20 times the depth of the water beneath it
Stratification:
layeres according to density; applies to fluids. Stable stratification occurs when density decreases continuously (but not necessarily uniformly) with distance fromt the Earth's center
Symbiosis:
an association between two species in which one or both benefit. A species in such an association that does not benefit may be harmed or may be unaffected by the association
Thermohaline Circulation:
the vertical movements of ocean water masses caused by density differences that are due to variations in temperature and salinty
Tide Gauges:
an instrument that measures the changes in sea surface that are caused by tides
Topography:
the configuration of a surface and the relations among its man-made and natural features
Trade-winds:
originally named by sailors, the trade-winds are a group of winds which blow from the east. The trade-winds are part of the Hadley cells which lie between 30 degrees North and 30 degrees South. The easterly trade-winds are the surface component of Hadley cells which due to the Coriolis effect move from the Northeast north of the Equator and from the Southeast south of the equator. Where the two sets of winds meet along the Equator the lack of persistent winds result in relative calm seas, this area is known by sailors as the doldrums. Air masses that move from subtropical high pressure belts toward the equator. They are northeasterly in the Northern Hemisphere and southesterly in the Southern Hemisphere
Trough:
the part of the ocean wave that is displaced below the still water line
Tsunami:
a long-period gravity wave generated by a submarine earthquake or volcanic event
Turbulence:
the flow of a fluid in which random velocity fluctuations distort and confuse the flow lines of individual molecules
Undercurrents:
a current below another current or beneath a surface
Upwelling:
a current of cold, nutrient-rich water rising to the surface. Upwellings are caused by strong seasonal winds moving surface coastal water out from the coast and leaving a space that the upwelling fills in. Many marine plants and animals live off this nutrient-rich water. Upwelling describes an ocean condition in which the cooler, nutrient-rich waters beneath the thermocline are drawn upwards to replace the warmer, surface waters which have been displaced by surface winds. vertical upward movement of a fluid due to density differences or where two fluid masses converge, displacing fluid upward. In the ocean, oftenrefers to where Ekman transport causes surface waters to diverge or move away from the coast and deeper (often cold and nutrient-rich) water to be brought ot the surface.
Wave-Height:
vertical distance between a crest and the preceding trough
Wave-Length:
the distance in a periodic wave between two points of corresponding phase in consecutive cycles
Wave Period:
the time that elapses between the passage of two successive wave crests past a fixed point
Wind Belts:
the influence of the Earth's rotation on winds
Wind Duration:
how long the wind blows
Wind Velocity:
the speed at which the wind moves in a particular direction
Zooxanthellae:
a form of algae that lives symbiotically in the tissue of corals and other animals and provides some of the coral's food supply by photosynthesis

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Revised on: 6 September, 2004

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