Oceanography: Origins And Elements

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Nautical Mile

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One Minute of arc length of latitude/longitude at the equator.

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Bathymetry

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The measurement of the depth of the ocean.

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Great Circle

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Any circle at Earth's surface with its center at Earth's center.
All longitude lines form great circles; only the equator is a great circle of latitude.

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Zenith

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Highest elevation above a reference longitude.

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Seismic Waves

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Movements in the Earth generated by earthquakes, volcanic eruptions, and humanmade explosions.

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P-Waves

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Primary Waves
~Travel faster than any other seismic waves and are the first to arrive at a recording station as they travel through all three states of matter.
~Compressional waves

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S-Waves

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Secondary Waves
~Travel more slowly than P-Waves and are the second waves to arrive at a station only through solids.
~Shear waves

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The Principle of Isostasy

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The distribution of elevated continents and depressed ocean basins requires that a balance be kept between the internal pressures under the land blocks and those under the ocean basins.
(Compare to the floating of an iceberg... The balance of the crust above and below sea level on the mantle.)

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Sediment

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A thick layer of loose particles over regions of the sea floor.

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The Theory of Plate Tectonics

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The incorporated ideas of continental drift and seafloor spreading in a unified model.

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Divergent
(Ocean-Ocean)

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*New seafloor created, ocean basin opens
*Mid-ocean ridge
*Shallow earthquakes and Volcanism
*ex. mid-atlantic ridge

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Divergent
(Continent-Continent)

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*Continent breaks apart, new ocean basin forms
*Continental rift, shallow sea
*Shallow earthquakes and Volcanism
*ex. Red Sea, East African Rift

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Convergent
(Ocean-Ocean)

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*Old sea floor destroyed by subduction
*Ocean trench
*Shallow to Deep earthquakes and Volcanism
*ex. Mariana Trench

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Convergent
(Ocean-Continent)

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*Old sea floor destroyed by subduction
*Ocean trench
*Shallow to deep earthquakes and Volcanism
*ex. Peru-Chile and Middle-America Trenches

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Convergent
(Continent-Continent)

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*Mountain building
*Mountain range
*Shallow to intermediate earthquakes and NO volcanoes
*ex. Himalaya Mountains, Alps

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Transform
(Ocean)

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*Sea floor conserved (neither created nor destroyed)
*Transform fault
*Shallow earthquakes, but NO volcanoes
*ex. Mendocino Fracture Zone off of the Calif. coast

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Transform
(Continent)

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*Sea floor conserved (neither created nor destroyed)
*Transform fault
*Shallow earthquakes, but NO volcanoes
*ex. San Andreas Fault

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Hydrothermal Vents

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*Plumes of hot water rising along rifts.
*Types: Clear, White smokers, and Black smokers
*Known to sustain life

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Fathom

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The length between a person's fully outstreched hands, standardized at 6 feet.

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Continental Margin

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The edges of landmasses below the ocean surface and the steep slopes that descend to the sea floor.
Passive/Atlantic and Active/Pacific

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Abyssal Hills and Seamounts

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Scattered across the sea floor in all the oceans, the former are less than 1000m high and the latter are steep-sided volcanoes.
They make up a majority of both the Pacific and Atlantic oceans.

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Guyots

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Submerged, flat-topped seamounts.

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Sediment Types

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*Lithogenous (derived from preexisting rocks, volcanoes, and airborne dust)
*Biogenous (derived from organisms)
*Hydrogenous (derived from chemical reactions in the Water)
*Cosmogenous (derived from space)

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Physical States of Water

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*Gas, Liquid, Solid
*The only substance that occurs naturally in three states on Earth's surface.

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Specific Heat

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*One calorie per gram of water per °C
*Prevents large variations of surface temperature in the oceans and atmosphere.

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Surface Tension

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*Elastic property of water surface. A measure of how difficult it is to stretch or penetrate the surface of a liquid.
*Important in water surface processes

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Latent Heat of Fusion

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*Heat required to change a unit mass from a solid to a liquid without changing temperature.
*Moderates the temperature of polar seas.

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Latent Heat of Vaporization

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*Heat required to change a unit mass from a liquid to a gas without changing temperature.
*The absorption of heat during vaporization important in controlling sea surface temperature and the transfer of heat in the atmosphere.

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Compressibility

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*Average pressure on total ocean volume 200 atmospheres
*Sinking water can warm slightly due to this.

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Density

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*Controlled by temperature, salinity, and pressure.
*Affects ocean temperature distribution.

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Viscosity

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*Liquid property that resists flow.
*Some motions of water are considered friction free. Low friction dampens motion; retards sinking rate of single-celled organisms.

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Attenuation

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Light absorbed and scattered by water molecules, ions, and suspended particles, including silt and micro-organisms decrease the intensity of light over a distance.

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Cation

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A charged atom or group of atoms.
An ion with a positive charge.

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Anion

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An atom with a negative charge.

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Major Constituents

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Chloride
Sodium
Sulfate
Magnesium
Calcium
Potassium

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Conservative Constituents

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Major Constituents are also known as these because their ratios do not change with the changes in total salt content and because they are not usually affected by organisms.

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Nonconservative Constituents

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Smaller quantities of these do change in concentrations because of biological and chemical processes that occur in some areas of the oceans.

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Adsorption

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The adherence of ions and molecules onto a particle's surface, removes other ions and molecules from seawater.
For example, tiny clay particles from rivers come to the oceans and bind ions such as potassium.

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Evaporites

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Salts left behind as sedimentary deposit.
Over geologic time, shallow arms of the sea have become isolated to produce these. (Red Sea)

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Residence Time

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The average time that a substance remains in solution in the ocean.

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Principle of Constant Proportion

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Seawater, regardless of variations in salinity, will maintain the ratios between the amounts of major ions in open-ocean (not near shore) waters as constant.

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Saturation Concentration

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The maximum amount any gas can be held in solution.
This changes as it depends on the temperature, salinity, and water pressure.

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Anoxic

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Stripped of dissolved oxygen.

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Anaerobic

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Nonoxygen-using.
(applies to some bacteria)

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Biological Pump

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The transfer of carbon from CO2 to organic molecules by photosynthesis resulting in the addition of CO2 to the mid-to-deep ocean water when organic material sinks and decays.

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Shelf Break

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The point at which the gradual slope of the shelf floor steepens rapidly.

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Barrier Reef

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This is formed when the coral is separated from the island by a lagoon

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Solar Constant

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The intensity of solar radiation directed towards the Earth.
It is 2 calories per square centimeter per minute.

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Heat Budget

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The gains and losses in heat by the Earth from and to space.
It helps maintain the long-term mean surface temperature of the earth at 16 deg. C.

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Reradiation

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The return of solar radiation to outer space.

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Troposphere

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The lowest layer of the atmosphere.
Here, the temperature decreases with altitude [increase] up to 12km or 7mi.

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Stratosphere

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The layer above tropopause.
Here, temperature increases with increasing altitude until reaching stratopause at 50km or 30mi.

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Ozone

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A highly reactive form of oxygen found principally in the stratosphere.

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Atmospheric Pressure

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The force with which a column of overlying air pushes on an area of Earth's surface.

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Isobar

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Lines of constant pressure marking atmospheric pressure distribution on weather charts.

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Coriolis Effect

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The apparent deflection of the moving air relative to Earth's surface.

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Trade Winds

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Bands of air deflected towards the Equator from the East.

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Challenger Expedition

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*Deep-sea water samples
*Investigated deep-water motion
*made temperature measurements at all depths
*Identified major elements in the seawater/chemistry