Absorption The penetration of one substance into a second substance
Abyssal hills Relatively small topographic features of a dominantly flat, deep-ocean floor, commonly 50-250 m in height and a few kilometers in width. They are most typical of the Pacific Ocean floor at depths of 3000-6000 m.
Abyssal plains A flat or very gently sloping area of the ocean basin floor, reaching to depths of between 2,200 and 5,500 m. Abyssal plains lie between the foot of a continental rise and a mid-oceanic ridge.
Albedo The amount of light reflected from an unpolished surface.
Alchemists People who believed that they could extract precious metals from seawater.
Altocumulus A cloud formation of rounded, fleecy, white or gray masses.
Altostratus An extended cloud formation of bluish or gray sheets or layers.
Ammonia a pungent gas compounded of nitrogen and hydrogen
Anticyclonic winds a large system of winds that rotates around a center of high barometric pressure, moving clockwise in the Northern Hemisphere and counterclockwise in the Southern, and usually produces cool, dry weather.
Aqueducts A raised canal, usually supported by arches, that carries water or other liquids from one place to another. The first aqueducts were designed by the ancient Romans.
Aquifers A geological formation or structure that stores and/or transmits water, such as to wells and springs.
Atmosphere The envelope of gases surrounding the earth and held to it by the force of gravity. Consists of four layers: the troposphere (about 5-10 miles above the earth), the stratosphere ( up to about 30 miles), the mesosphere (up to about 60 miles), the thermosphere (up to about 300 miles or more).
Atmospheric pressure the applying of constant force upon a surface.
Auroral ovals Refers to the areas in either north or south pole where the solar winds interacts with the magnetic force of the Earth, causing spectacular skies.
Authigenic deposits Forming in place


Barometer A meteorological instrument that measures atmospheric pressure. Used to predict weather changes.
Bathymetry The measurement of the depth of the ocean floor from the water surface; the oceanic equivalent of topography
Bernoulli's principle The principle of conservation of energy applied to fluid flow; speed increases while air pressure decreases. Named after Daniel Bernoulli.
Biochemical the science of the chemistry of living things.
Biogenic deposits The formation of rocks, traces, or structures as a result of the activities of living organisms.
Bore Very rapid rise of the tide, in which the advancing flood waters form a wave with an abrupt front.
Braided Stream whose plan form consists of a number of small channels separated by bars (typically constructed of gravel, often regularly spaced, and forming a riffle or shallow section).


Calcareous sediments Composed of, containing, or characteristic of calcium carbonate, calcium, or limestone; chalky.
Canopy A forest's second layer, or roof. Consists of a network of branches and leaves, forms a covering that blocks some of the sunlight from lower plants
Carbon dioxide a colorless gas formed in the tissues during metabolism and carried in the blood to the lungs, where it is exhaled.
Carbon monoxide a colorless, odorless, combustible, and very poisonous gas, produced by the incomplete combustion of material containing carbon, such as gasoline, because of insufficient air.
Carbonate compensation depth The depth in the sea at which the rate of dissolution of solid calcium carbonate equals the rate of supply. Surface ocean waters are usually saturated with calcium carbonate, so calcareous materials are not dissolved. At mid-depths the lower temperature and higher CO2 content of seawater cause slow dissolution of calcareous material. Below about 4500 m waters are rich in dissolved CO2 and able to dissolve calcium carbonate readily. Carbonate-rich sediments are common in waters less than 3500 m depth, but are completely absent below about 6000 m.
Centripetal force A force that tends to pull a particle or body toward the axis around which it rotates.
Channels A bed or stream of a waterway.
Chlorofluorocarbons A series of hydrocarbons containing both chlorine and fluorine. These have been used as refrigerants, blowing agents, cleaning fluids, solvents, and as fire extinguishing agents. They have been shown to cause stratospheric ozone depletion and have been banned for many uses.
Cirrostratus A high-altitude, thin, hazy cloud, usually covering the sky and often producing a halo effect.
Cirrus A high-altitude cloud composed of narrow bands or patches of thin, generally white, fleecy parts
Clay deposits Sediments that are very fine grained; mud deposits.
Climate The meteorological conditions, including temperature, precipitation, and wind, that characteristically prevail in a particular region.
Coalescence To grow together; fuse.
Cold front The leading portion of a cold atmospheric air mass moving against and eventually replacing a warm air mass; cold air.
Condensation The process by which a gas or vapor changes to a liquid.
Continental margins Zone that consists of the continental shelf, continental slope, and continental rise. It extends from the shoreline to the deep-ocean floor at a depth of 2000 m. The zone is underlain by continental crust. Continental margins have been divided into active margins or passive margins depending on their coincidence, or otherwise, with plate margins.
Continental shelf Gently seaward-sloping surface that extends between the shoreline and the top of the continental slope at about 150 m depth
Convection The transfer of heat or other atmospheric properties by massive motion within the atmosphere, especially by such motion directed upward.
Coriolis effect Physics an effect whereby a body moving relative to a rotating frame of reference is accelerated in a direction perpendicular both to its direction of motion and to the axis of rotation of the frame. The effect helps to explain global wind patterns (rotating clockwise in the northern hemisphere, anticlockwise in the southern) and the trajectories of rockets over the Earth's surface.
Corrosive capable of causing or tending to cause corrosion; eat away usually caused by chemical reactions.
Covalent bond A type of chemical bond in which atoms are held together in a molecule by sharing one or more pairs of electrons in their outer shells.
Cumulonimbus An extremely dense, vertically developed cumulus with a relatively hazy outline and a glaciated top extending to great heights, usually producing heavy rains, thunderstorms, or hailstorms.
Cumulus A dense, white, fluffy, flat-based cloud with a multiple rounded top and a well-defined outline, usually formed by the ascent of thermally unstable air masses.
Cyanobacteria A photosynthetic bacterium, generally blue-green in color and in some species capable of nitrogen fixation.
Cyclones A violent tropical storm, especially one originating in the southwestern Pacific Ocean or Indian Ocean.
Cyclonic winds Low pressure at the center and high pressure on the outside, causes movement; counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.


Dendritic Generally, tree-like, branching.
Dew Water droplets condensed from the air, usually at night, onto cool surfaces.
Diarrhea Frequent passage of loose watery stools, commonly the result of intestinal infection. Severe diarrhea in children can lead to dehydration and death;
Dissolution Dissolution is the taking into solution of simple or complex ions, such as when calcite is dissolved by water and carbonic acid.
Divide A ridge of land that separates two drainage areas or watersheds.
Doldrums The ocean belt near the equator, characterized by calms and light, variable winds, or the characteristic weather of this region.
Drainage basin Land area where precipitation runs off into streams, rivers, lakes, and reservoirs.
Dredge A machine (commonly on a boat) used to scoop up mud, gravel, or obstructions from the bottom of rivers, docks, etc., so as to deepen them.


Easterlies Coming or being from the east: easterly winds.
Ebb tide Falling tide: the phase of the tide between high water and the succeeding low water.
Eddies Motion of a fluid in directions differing from, and at some points contrary to, the direction of the larger-scale current.
Ekman spiral Theoretical model to explain the currents that would result from a steady wind blowing over an ocean of unlimited depth and extent.
El Nino A warming of the ocean surface off the western coast of South America that occurs every 4 to 12 years when upwelling of cold, nutrient-rich water does not occur. It causes die-offs of plankton and fish and affects Pacific jet stream winds, altering storm tracks and creating unusual weather patterns in various parts of the world.
Electromagnetic waves A wave that consists of an electric field in conjunction with a magnetic field oscillating with the same frequency; Of, Pertaining to, or produced by, magnetism which is developed by the passage of an electric current.
Emergent coastline Coastline that is rising in elevation in geologic time.
ENSO El Nio Southern Oscillation
Ephemeral lasting for only a short period.
Erlenmeyer flask a conical laboratory flask with a broad, flat base and a short, narrow neck, used to mix liquids by hand.
Evaporation To convert or change into a vapor.
Exosphere The outermost, least dense portion of the atmosphere.


Fathom A unit used to express depths of water. Originally intended to be the distance between a man's fingertips with his arms outstretched, it is equal to six feet.
Flash floods A sudden flood of great volume, usually caused by a heavy rain.
Flooding To become inundated or submerged.
Fog Condensed water vapor in cloudlike masses lying close to the ground and limiting visibility.
Fracture zones A linear feature on the deep-sea floor across which the lithosphere changes abruptly in both age and water depth.
Fractured Cracks in rock.
Front The interface between air masses of different temperatures or densities.
Frost A deposit of minute ice crystals formed when water vapor condenses at a temperature below freezing


Glacial deposits Glacial deposit consisting of boulders of varying size in a clay-dominated matrix, and laid down beneath a valley glacier or ice sheet.
Greenhouse effect An effect occurring in the atmosphere because of the presence of certain gases that absorb infrared radiation.
Groundwater The water that has percolated into the ground and become trapped within pores, cracks, and fissures.


Habitat The place in which an organism lives defined by the food, space, microclimate, other organisms, and physical and chemical conditions that it provides.
Hail A precipitation from clouds in pellets of ice and hard snow.
High pressure An air mass of higher than normal pressure;
Homogeneous Of the same kind; consisting of parts all of the same kind; uniform.
Humidity Dampness, especially of the air; wetness in the atmosphere
Hurricanes A wind with a speed greater than 74 miles (119 kilometers) per hour, according to the Beaufort scale.
Hydrocarbons Any of various organic compounds that contain only hydrogen and carbon, such as methane or ethylene.
Hydrogen bond a weak electrostatic bond formed by linking a hydrogen atom between two electronegative atoms
Hydrologic Representation of the flow of water in various states through the terrestrial and atmospheric environments. Storage points (stages) involve groundwater and surface water, ice-caps, oceans, and the atmosphere.
Hydrologic cycle The cyclic transfer of water vapor from the Earth's surface via evaporation or transpiration into the atmosphere, from the atmosphere via precipitation back to earth, and through runoff into streams, rivers, and lakes, and ultimately into the oceans.
Hydrophilic Describing a molecule or part of a molecule that has an affinity for water.
Hydrophobic An interaction between a hydrophobic ('water-hating') part of a molecule and an aqueous environment.
Hydrosphere The whole body of water that exists on or close to the surface of the Earth. This includes the oceans, seas, lakes, and the water in the atmosphere


Infiltration Flow of water from the land surface into the subsurface.
Intermittent stream . A stream which ceases to flow in very dry periods. Such streams tend to have permeable beds and during periods of flow water leaking through their beds is added to the local groundwater
Interplanetary Existing, occurring, or functioning between planets.
Ionosphere Layers of the Earth's atmosphere located above the stratosphere from about thirty to two hundred and fifty miles above the earth's surface, and composed of rarefied gases that have been ionized by radiation from the Sun.
Ions An electrically charged particle created in a gas, as by an electric discharge.


Jet stream A narrow band of westerly high velocity wind, in excess of 95 mph (150 kph), that encircles the earth in the upper troposphere. It can reduce the flying time across the Atlantic Ocean from west to east and retard flights in the opposite direction.




Larvae The immature form of many animals, which hatches from the egg and often differs in appearance from the adult form.
Lightning bolt An abrupt, discontinuous natural electric discharge in the atmosphere.
Lithosphere The upper (oceanic and continental) layer of the solid Earth, comprising all crustal rocks and the brittle part of the uppermost mantle.
Low pressure An air mass of lower than normal pressure; often brings precipitation.


Magnetosphere A region between five hundred and several thousand miles above the earth's surface, in which charged particles are trapped by the Earth's magnetic field.
Manganese nodules An irregular lump of rock containing manganese, found on the deep ocean floor, particularly the north Pacific.
Mariners Seaman.
Meander A sinuous curve in a river.
Mesosphere The Earth's atmosphere between the stratosphere and the thermosphere, or from twenty miles to fifty miles above the earth's surface.
Meteorology The science that deals with the phenomena of the atmosphere, especially weather and weather conditions
Methane A flammable hydrocarbon gas that results from the decay of organic material as in marshes and coal mines, and is the main constituent of natural gas.
Mid-oceanic ridge A long, linear, elevated, volcanic structure often lying along the middle of the ocean floor.
Monsoon A wind from the southwest or south that brings heavy rainfall to southern Asia in the summer.


Nimbostratus A low, gray, often dark cloud that precipitates rain, snow, or sleet.
Nitrogen oxides Inorganic oxides that contain nitrogen.
Nomads Peoples who live in no fixed place but wander periodically according to the seasonal availability of food, and pasture,


Occluding To force (air) upward from the Earth's surface, as when a cold front overtakes and undercuts a warm front.
Ocean Large expanse of sea including the Atlantic, Pacific, Indian, Arctic, and Antarctic Oceans.
Oceanography The study of the oceans.
Opaline silica Silica dioxide with water inside the molecule
Oxygen A colorless, odorless gas, and the most abundant element on Earth, occurring in the crust, in fresh water and sea-water, and in the atmosphere, of which it forms 21 per cent by volume.
Oxygen minimum level Organisms on the surface of bodies of water use the oxygen for their metabolism. As you go down in the water column there is a place where the dissolved oxygen in the water is at its lowest concentration.
Ozone A form of oxygen, and an atmospheric trace gas, made by natural photochemical reactions associated with solar ultraviolet radiation.


Paradox A statement that contradicts or seems to contradict itself, yet often expresses a truth, such as "Less is more".
Particulates Of, relating to, or formed of minute separate particles.
Percolates Filter through a substance
Perennial A stream that would normally be expected to flow throughout the year.
Phlogiston theory A theory of combustion introduced by Johann Becher (1635-82) and refined by Georg Stahl in about 1700. It assumes that all combustible substances contain phlogiston, which is liberated when the substance is heated, leaving calx or ash. The theory was finally overthrown in the late 18th century by Antoine Lavoisier, who correctly explained combustion in terms of oxidation.
Photochemical The scientific study of the chemical action and effects of light.
Photosynthesis The process in plants by which sunlight, with the help of chlorophyll, is converted to chemical energy that is used to synthesize inorganic compounds into organic ones, esp. sugars.
Photosynthetic Process in which the energy of sunlight is used by organisms, esp. green plants, to synthesize carbohydrates from carbon dioxide and water.
Plasma particles An electrically neutral, highly ionized gas composed of ions, electrons, and neutral particles. It is a phase of matter distinct from solids, liquids, and normal gases.
Pools Any small area of liquid that has collected on a surface; puddle; pond.
Porosity The state, quality, or condition of being porous (highly absorbent or permeable).
Pressurized air Air molecules that is confined to a small space, by either reduction in volume or through temperature difference.
Proterozoic Formed in the later of two divisions of the Precambrian era; from 600 million to 1.5 billion years ago; bacteria and fungi; primitive multicellular organism




Radiation Energy travelling in the form of electromagnetic waves or photons; the spread of energy from some source through space or matter.
Radio waves An electromagnetic wave of a frequency arbitrarily lower than 3000 GHz.
Reservoirs Natural or artificial lakes in which water is stored for irrigation, to supply water for municipal needs, for hydroelectric power, or to control water flow.
Resistance The act or process of resisting; the opposition posed by one force against another.
Riffles Shallow disturbed part of a stream
Riparian Of, on, or relating to the banks of a natural course of water.
Runoff The flow across the land surface of water that accumulates on the surface when the rainfall rate exceeds the infiltration capacity of the soil.


Salinity Measure of the total quantity of dissolved solids in sea water in parts per thousand by weight when all the carbonate has been converted to oxide, the bromide and iodide to chloride, and all the organic matter is completely oxidized. Ocean-water salinity varies in the range 33-8 parts per thousand, with an average of 35 parts per thousand.
Sargasso sea An elliptical section of the N Atlantic Ocean between latitudes 20N and 35N and longitudes 30W and 70W. Contained within a current system, it is still and warm. It takes its name from the floating brown seaweed of the genus Sargassum (gulfweed), found in it.
Satellites A man-made spacecraft that orbits the earth, moon, sun, or a planet.
Sea Large body of salt water.
Sediment cores Slices of the layers of the Earth, usually taken with a hollow tube
Sewage Waste matter from industrial and domestic sources that is dissolved or suspended in water.
Siliceous sediments Applied to a sediment which comprises particles composed of silicate minerals and rock fragments, i.e. mudstones, sandstones, and conglomerates.
Smog A haze caused by the effect of sunlight on foggy air that has been polluted by vehicle exhaust gases and industrial smoke.
Solar radiation All the radiation that comes from the Sun.
Sonar A technique, similar in principle to radar, for finding the distance and direction of a remote object in water by transmitting sound waves and detecting reflections from it.
Specific heat The quantity of heat needed to raise a unit mass of substance by 1C. It is measured in joules per kelvin per kilogram.
Spring A natural fountain that comes from the rocks just below the surface of the Earth; a source of a body or reservoir of water.
Storm surge When a storm (i.e. hurricane) causes water to "pile" up and move as a wall of water.
Stratocumulus. A low-lying cloud formation occurring in extensive horizontal layers with rounded summits
Stratopause The level that marks the maximum height of the stratosphere, at around 50 km.
Stratosphere The layer of the Earth's atmosphere that lies above the troposphere and extends to about 50 km above the earth's surface. The temperature within the stratosphere remains fairly constant but can rise in the upper regions of this layer due to absorption of ultraviolet radiation by ozone.
Streambed The channel through which a natural stream of water runs or used to run.
Stromatolites A widely distributed sedimentary structure consisting of laminated carbonate or silicate rocks, produced over geologic time by the trapping, binding, or precipitating of sediment by groups of microorganisms, primarily cyanobacteria.
Sublimation a change directly from the solid to the gaseous state without becoming liquid
Submarine canyon Deep, steep-sided valley cut into the continental shelf or slope, whose axis slopes seaward at up to 80 m/km.
Submarines A vessel, especially a warship, capable of operating under water and usually equipped with torpedoes, missiles, and a periscope.
Submergent coastlines When land loses height, where the ocean can drown the land. Most of the eastern United States has submergent coastlines.
Suffocates To die from lack of oxygen; to be smothered, stifled, suppressed, or deprived of cool fresh air.
Sulfur oxides Inorganic oxides of sulfur.
Surface tension The attraction of molecules to each other on a liquid's surface. Thus, a barrier is created between the air and the liquid.


Terrigenous deposits The description of a sediment which has been deposited, or formed, on land.
Thalweg Line joining the lowest points of successive cross-sections, either along a river channel or, more generally, along the valley that it occupies.
Thermometer An instrument for measuring temperature, especially one having a graduated glass tube with a bulb containing a liquid, typically mercury or colored alcohol, that expands and rises in the tube as the temperature increases.
Thermosphere The extreme outer edge of the earth's atmosphere, within which temperature increases steadily with altitude.
Thunderstorms A transient, sometimes violent storm of thunder and lightning, often accompanied by rain and sometimes hail.
Tides The regular rising and falling of seawater resulting from the gravitational attraction between the Earth, Sun, and Moon.
Topography detailed description, representation on a map, etc., of the features of a town, district, etc.
Tornadoes A rotating column of air ranging in width from a few yards to more than a mile and whirling at destructively high speeds, usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud.
Torrential rains Lots of rain with high winds
Trade winds Any of a consistent system of prevailing winds occupying most of the tropics, constituting the major component of the general circulation of the atmosphere, and blowing northeasterly in the Northern Hemisphere and southeasterly in the Southern Hemisphere.
Trenches A deep narrow depression in the ocean floor, often thousands of meters deep. Trenches usually form near the edge of a continent where the tectonic plate carrying the ocean is being subducted beneath the continental plate.
Tributaries River or stream flowing into a larger river or lake.
Troposphere The lower layer of the atmosphere, extending to 16 km above ground level at the equator, 11 km at 50 N and S, and 9 km at the poles. Most clouds and precipitation, and, indeed, weather events, occur within this layer.
Typhoons A tropical cyclone occurring in the western Pacific or Indian oceans.


Ultraviolet radiation Having or employing wavelengths shorter than light but longer than X-rays; lying outside the visible spectrum at its violet end
Upwelling A process in which cold, often nutrient-rich waters from the ocean depths rise to the surface


Vacuum an enclosed space or container from which air has been removed; a space empty of all matter.
Vaporization To convert or be converted into vapor.
Viscosity The property of a fluid that determines the ease or difficulty with which it flows.


Warm front A front along which an advancing mass of warm air rises over a mass of cold air
Water mass A mass of water that has similar physical characteristics, i.e. temperature, salinity
Watershed The land area that drains water to a particular stream, river, or lake. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge. Large watersheds, like the Mississippi River basin contain thousands of smaller watersheds.
Weather The state of the air or atmosphere with respect to heat or cold, wetness or dryness, calm or storm, clearness or cloudiness, or any other meteorological phenomena.
Westerly Coming or being from the west: westerly winds.
Wind The horizontal movement of air over the Earth's surface and one of the basic elements of weather. Thermal differences throughout the world produce variations in air pressure and air will flow generally from high-pressure to low-pressure areas.