Initial Publication Date: March 3, 2006

Earth System Science Vocabularies Part II: Earth System Processes

Planetary Formation

accretion (planetary): The process whereby small particles and gases in the solar nebula came together to form larger bodies, eventually of planetary size
geodynamics: the physical processes within the Earth as they affect the features of the crust
differentiation: Processes by which multiple rock types form from a single magma
convection: Transfer of heat in a fluid by the circulation flow due to temperature differences resulting in density differences
phase transformation: Change of a crystal from one polymorph to another, or of a compound from one state to another
volcanism: The processes by which magma and its associated gases rise into the crust and are extruded onto the Earth's surface and into the atmosphere
magmatism: The development and movement of magma and its solidification to igneous rock
plutonism: The general term for the phenomena associated with the formation of plutons (i.e. intrusive igneous rocks)
orogeny: Processes that lead to the formation of mountains. The process by which structures within fold-belt mountainous areas were formed, including thrusting, folding, and faulting in the outer and higher layers, and plastic folding, metamorphism, and plutonism in the inner and deeper layers
epeirogeny: Vertical (upward or downward) processes that produce continent-scale features such as plateaus and basins
anorogenic processes: Processes not related orogenic disturbance; e.g. an anorogenic pluton
isostasy: Condition of equilibrium,equivalent to floating; e.g. units of the lithosphere above the athenosphere

Plate Tectonics

A theory of global tectonics in which the lithosphere is divided into a number of plates whose pattern of horizontal movement is that of torsionally rigid bodies that interact with one another at their boundaries, causing seismic and tectonic activity along those boundaries

Plate Boundary Processes

convergent margin processes: A boundary between two plates that are moving toward each other; synonymous with subduction zone, active margins; inclusive of subduction, high pressure metamorphism, and calc-alkaline magmatism
subduction: The process of one lithospheric plate descending beneath another
obduction: The overriding or overthrusting of oceanic crust into the leading edges of continental lithospheric plates
continental collision: The edges of two continents, each on a different plate, colliding with each other resulting in deformation, metamorphism and magmatism
divergent margin process: A boundary between two plates that are moving apart from each other, with mantle material and new oceanic crust moving in to fill the gap; inclusive of sea-floor spreading
sea floor spreading: The theory that the oceanic crust is increasing in area by upwelling of magma along the mid-ocean ridges
transform fault margin processes: A plate boundary at which lithosphere is neither created nor destroyed; plates slide past each other on a strike-slip fault; inclusive of transform or strike-slip fault processes
accretion (geologic): The addition of volcanic arc or continental material to a continent by convergent and transform motion, i.e. by collision and welding or suturing

Plate Interior Processes

plume: A localized body of volcanic rock rising into the crust from the mantle and thought to be the causal mechanism of a hot spot
rift/rifting: A long, narrow continental trough that is bounded by normal faults, a graben of regional extent; lithosphere has ruptured under extension
isostasy: A condition of equilibrium comparable to floating, of the units of the lithosphere above the asthenosphere; down- or upwarping

Evolution of Earth's Surface

Physical Processes

erosion: General processes whereby the materials of the Earth's crust are loosened, dissolved, or worn away, and simultaneously moved from one place to another
transportation: The movement by natural agents (e.g. wind, water, glacier) of sediment of any loose material as solid particles or in solution from one place to another
deposition: The accumulation of Earth materials, e.g. mechanical settling of sediments from suspension in water, chemical precipitation of minerals
sedimentation: The act or process of forming or accumulating sediments in layers, including such processes as the separation of rock particles from the material from which the sediment is derived, the transportation of these particles to the site of deposition, the actual deposition or settling of the particles, the chemical and other diagenetic changes occurring in the sediment and the ultimate consolidation of the sediment into rock
lithification: The conversion of a newly deposited, unconsolidated sediment into a coherent, solid rock, involving processes such as cementation, compaction, desiccation and crystallization
hydrologic (water) cycle: The constant circulation of water from the sea, through the atmosphere, to the land, and its eventual return to the atmosphere by way of transpiration and evaporation from the sea and land surfaces
fluvial: Pertaining to rivers; produced by the action of a stream or river
lacustrine: Pertaining to lakes
groundwater: That part of the subsurface water that is in the saturated zone; loosely, all subsurface water as distinct from surface water
shoreline processes: The intersection of a body of water with a shore or beach, e.g.long shore drift
glacial: Relating to the presence and activities of ice or glaciers
aeolian: Wind-borne transport of sediments; related to erosion and weathering, sediment transport, desertification, arid and semiarid ecosystems
mass wasting: General term for the dislodgement and downslope transport of soil and rock material under the direct application of gravitational body stresses; includes processes such as creep, solifluction, rock falls, rockslides, and debris flows
avalanche: A large mass of snow, ice, soil or rock, or mixtures of these materials, falling, sliding or flowing very rapidly under the force of gravity
meteorite impact: Solid object moving in interplanetary space (meteorite), colliding with the planet surface, usually with sufficient energy to produce an impact crater

Mechanical Processes

deformation: A general term for the process of folding, faulting, shearing, compression or extension (of rocks) as a result of various (earth) forces.
folding: Curving or bending planar structures such as rock strata, bedding planes, foliation, or cleavage
faulting: Movement of one rock mass past another along a discrete surface or zone
shearing: A deformation resulting from stresses that cause or tend to cause contiguous parts of a body to slide relatively to each other in a direction parallel to their plane of contact; refers to strain rather than stress
compression: A system of forces or stresses that tends to decrease the volume of, or shorten, a substance
extension: A strain term signifying increase in length; a measure of the change of length of a line
stress: In a solid, the force per unit area, acting on any surface within it, and expressed as pounds/sq inch, etc.
strain: The change in shape or volume of a body as a result of stress

Chemical Processes

rock cycle: The interrelationship between the Earth's internal and external processes. Relates the three rock groups - igneous, sedimentary, and metamorphic - to each other and to surficial processes such as weathering, transportation, and deposition, and to internal processes such as magma generation and metamorphism
melting: Transformation from a solid to a liquid state
crystallization: Transformation from a liquid or vapor to a solid state
metamorphism: Mineralogical, chemical and textural adjustment of solid rocks to physical and chemical conditions
dehydration: A (metamorphic) reaction that results in the transfer of H₂O to the fluid phase (geol)
solution: A homogeneous mixture of two or more components in a single phase, often refers specifically to a solution in water (an aqueous solution); a process of chemical weathering by which rock and mineral material passes into solution
precipitation (geol): The formation of an insoluble solid by a reaction which occurs in solution (geol)
oxidation/reduction reactions: Addition/loss of oxygen to a compound; any reaction which occurs in solution (geol)
diagenesis: All of the chemical, physical and biological changes undergone by a sediment after its initial deposition, and during and after its lithification. Includes compaction, cementation, reworking, authigenesis, replacement, crystallization, leaching, hydration, bacterial action, and formation of concretions
weathering: Physical disintegration or chemical decomposition of rock
pedogenesis: soil formation

Biogeochemical Processes

carbon cycle: A biogeochemical cycle that consists of the continuous movement of carbon in its many chemical forms from one reservoir to another; reservoirs include the atmosphere, lithosphere, biosphere and hydrosphere. The exchanges of carbon between reservoirs are governed by various physical, chemical, and biological processes, as well as by human intervention.
nitrogen cycle: The sum total of the transformations undergone by nitrogen and nitrogenous compounds in nature in relation to living organisms

Biological Processes

biomineralization: The process by which organisms fix minerals in their skeletons or internal organs
biogenesis: Formation by the action of organisms (e.g. coral reefs)
bioleaching: The use of organisms such as bacteria to facilitate leaching, e.g. of an ore
bioturbation: The churning and stirring of a sediment by an organism
fossilization: All processes involving the burial of a plant or animal in sediment and the eventual preservation of all, part, or a trace of it
photosynthesis: Biological process whereby carbon dioxide is converted to organic matter in the presence of light; oxygen gas can also be produced
chemosynthesis: Energy drived from chemical reactions (e.g. oxidation of sulphur or of ammonia) in the synthesis from inorganic moleculres oftheir organic requirements
fixation: The conversion of an inorganic source of an element (like N or C) into an organically useful form

Ecosystem Processes

evolution: The theory that life on Earth has developed gradually, from one or a few simple organisms to more complex organisms; the change of a group of related organisms toward adaptation to the environmental conditions to which they have been exposed with the passage of time
adaptation: Any morphological, physiological or behavioral characteristic which fits an organism to the conditions under which it lives
natural selection: Evolutionary theory which postulates the survival of the best adapted life forms, with inheritance of those characteristics wherein their fitness lies, and which arise as random variations due to mutation
mutation: A change, spontaneous or induced, that converts one allele into another; any change of a gene or of chromosomal structure or number
extinction: The total disappearance of a species or higher taxon
dispersion: The pattern of geographic or spatial distribution of individuals within a species; may be uniform, random or irregular, or aggregated or clumped
radiation of populations: The dispersal of a group of organisms into different environments often accompanied by divergent change in morphology (e.g. adaptive adiation)
ecological competition: e.g. from non-native species, exotic or invasive species

Anthropogenic Processes (Human Impacts)

habitat change: Change in the environment or place where an organism, species, or population tends to live; a locally circumscribed portion of the total environment
pollute: To make physically impure or unclean, synonymous with contaminate; to introduce any substance that alters some aspect of the environment in a manner to make it unfit for a particular use
anthropogenic contaminants: e.g. heavy metal release (mercury), organics (pesticide and herbicide)
mineral resources (extraction and exploitation): Naturally occurring mineral deposits; metal and nonmetallic minerals of economic value
energy resources (extraction and exploitation): Non-renewable, naturally occurring organic deposits such as oil, natural gas, coal; inorganic uranium resources. Renewable resources include e.g. wind, hydrothermal, hydrodynamic, tidal, and biomass
water resources (extraction and exploitation): Occurrence, replenishment, movement, discharge, quality and availability of water
exploration/discovery: The search for deposits of useful minerals, fossil fuels, water
extraction/development: Recovery of resources, separation and enrichment, for practical use
waste/disposal: Residual by-products related to extraction of resources
desertification: The progressive destruction or degradation of vbegetative cover especially in arid or semiarid rgions bordering existing deserts
deforestation: The removal of forests stands by cutting and burning to provide land for agricultural purposes, residential or industrial guildint sites, roads, etc.
urbanization: Transformation of natural lands to support human habitation; results in changes in land use and land cover

Interactive Processes

positive feedback: The process by which a change in one direction promotes continued change in the same direction
negative feedback: The process by which a change in one direction leads to events that reverse the direction of the change
chaos: Encompasses principles related to e.g., self-organization, sensitive dependence on initial conditions, strange attractors
fractal: A shape made of parts similar to the whole in some way; includes concepts of fractal dimensions, similarity and scaling

Oceans

surface circulation: Flow of water in the ocean, driven by drag of air currents, typically no more than 50-100 meters deep
eddy/gyre: The local containment of water to a confined region, due to a small-scale circulation system
coriolis Effect: An effect that causes any body that moves freely with respect to the rotating solid Earth to veer toward the right in the northern hemisphere and toward the left in the southern hemisphere, regardless of the initial direction of the moving body
Ekman Transport: The average flow of water over the full depth of the Ekman spiral, a current pattern from the water's surface to deeper layers, caused by the Coriolis effect, as each successive, slower moving layer of water is shifted to the right
thermohaline circulation: Global patterns of water circulation propelled by the sinking of dense cold and salty water
El Nino/La Nina/ENSO: A cyclic phenomena in the Pacific Ocean, characterized by relatively large differential values across the Pacific in temperature, rainfall, and reduction or reversal of the trade winds, occurring every several years.
upwelling: The process by which subsurface waters flow upward and replace the water moving away; rising of cold, heavy, subsurface water toward the surface, especially along the western coasts of continents; it replaces surface water that it transported away from the coast by the action of winds parallel to it or by diverging currents
downwelling: The process by which surface water becomes more dense and sinks
evaporation: The process by which a substance passes from the liquid or solid state to the vapor state; vaporization
hydrothermal circulation: Flow of water driven by igneous activity that involves heated or superheated water; e.g. submarine "vent" or "black smoker" deposits
marine transgression: Sea level rises with respect to a continent, the shoreline moves inland
marine regression: Sea level falls with respect to a continent, the shoreline moves in a seaward direction
sea level change: The long term change in global mean sea surface height, caused generally by melting or freezing of glaciers
deglaciation and impacts on ocean circulation: Climate-ice interactions; air-sea-ice exchange processes; ice age dynamics; paleoclimataic effects on continental collisions and glaciation
coral bleaching: The damage and eventual destruction of corals due to abnormally high temperatures
storm surge: The infiltration of waves onto coastal land, due to sever storm conditions
tide: Twice-daily variation in the ocean surface height due to the relative pull of the moon (and sun)
saltwater intrusion: Displacement of fresh water due to its greater density, usually in coastal and estuarine environments

Atmosphere

aurora: The energetic release of charged particles from the sun, visible as colorful sheet-like displays in high-latitudes
microscale processes: Processes that occur in an atmospheric layer ranging from a few centimeters to a few kilometers in the horizontal, and from the ground to a height of about 100 meters, where the surface loses its immediate influence in the surface boundary layer. It pertains to meteorological phenomena, such as wind circulations or cloud patterns, that are less than 2 km in horizontal extent
mesoscale processes: Processes that occur in the atmosphere with dimensions that range from a few kilometers to some tens of kilometers horizontally and, vertically, from the ground to the top of the Friction layer
mesoscale processes: Processes that occur in the atmosphere with dimensions that range from a few kilometers to some tens of kilometers horizontally and, vertically, from the ground to the top of the Friction layer. It includes local winds, thunderstorms, and tornadoes
synoptic processes: Processes that operate at the continental or oceanic spatial scale; include migratory cyclones, anticyclones, air masses, and fronts
convection: Transfer of heat in a fluid by the circulation flow due to temperature differences (resulting in density differences; atm)
conduction: The transfer of heat through a substance by molecular activity from one substance by being in contact with another
advection (atm): The horizontal transfer of any atmospheric property by wind
turbulence: Vertical motion of the air, at times violent, causes up and down movements
centrifugal force: Force directed outward, away from the center of a rotating object; equal in magnitude to the centripetal force but in the opposite direction
centrifgal force: Force directed inward that confines an object to a circular path; and is equal inmagnitude to the centrifugal force but in the opposite direction
global air circulation: Global-scale wind systems
microburst: An intense, localized downdraft of air that spreads on the ground, causing rapid changes in wind direction and speed; a localized downburst
Hadley cell circulation: Thermally driven and zonally symmetric circulation; a closed circulation system, consisting of the equatorward movement of the trade winds between a latitude of about 30^o and the equator in each hemisphere, with rising wind components near the equator, poleward flow aloft, and finally descending components at about 30^o latitude again.
hurricane/typhoon: An intense, low pressure center formed in the tropical and sub-tropical oceans, characterized by extremely high winds and continually fed by ocean moisture
tornado: A funnel formed by updrafts producing extremely high winds
evaporation: Phase transition of a liquid to form a gas
precipitation (atm): Formation of any form of water particles, whether solid or liquid, that fall from clouds and reach the ground
condensation (atm): Phase transition to form a liquid from a gas
accretion (atm): Growth of a precipitation particle by the collision of an ice crystal or snowflake with a super cooled liquid droplet that freezes upon impact
melting: Transformation from a solid to a liquid state
freezing: Phase transition from a liquid to form a solid
sublimation: Phase transition from a solid to form a gas
diffuse insolation: The solar radiation that is scattered or reflected by atmospheric components (clouds, for example) to the earth's surface
direct insolation: The solar radiation that is transmitted directly through the atmosphere to the earth's surface without interacting with atmospheric components
adiabatic processes: A process that occurs without gain or loss of heat to or from the system; in an adiabatic process, compression always results in warming, and expansion results in cooling
P/V/T processes: Work done by a system as indicated by expansion or contraction in response to changes in pressure and temperature
absorption: The process through which incident radiant energy is retained by a substance; the adsorbed radiation is then converted to another form of energy (e.g. heat)
adsorption: The adhesion of thin films of liquids or gases to a solid substance
scattering: The deflection of light in all directions; light is diffused or deflected by collisions with particls suspended in the atmosphere
reflection: The process whereby a surface turns back a portion of the radiation that strikes it
refraction: The bending of light as it passes from one medium to another
photodissociation: The splitting of a molecule into two or more neutral atoms or molecules by the absorption of a photon
air-sea exchange processes: Related to atmospheric circulation systems; sea salt aerosols; ocean circulation and climate
atmospheric fluid dynamics: Atmospheric circulation systems, atmospheric modeling, geophysical fluid dynamics
atmospheric circulation systems: Cloud dynamics, zonal and meridional winds, atmospheric fronts, fluid dynamics
atmospheric fronts: Atmospheric circulation systems, cloud dynamics, meteorology, fluid dynamics
air inverstion: A condition where surface air is trapped below upper layer air and is unable to mix and "cleanse"
subsidence (atm): The slow sinking of air, usually associated with high-pressure areas
entrainment: The mixing of environmental air into a preexisting air current or cloud so that the environmental air becomes part of the current or cloud
ozone: A form of oxygen, O₃. It is a powerful oxidizing agent that is considered a pollutant in the lower troposphere but an essential chemical in the stratosphere where it protects the earth from high-energy ultraviolet radiation from the sun
cloud dynamics: Atmospheric circulation systems, atmospheric fronts, clouds and their effect on climate; mid-latitude convective systems; mountains and orographic effects on airflow and precipitation; Polar stratospheric clouds
lightning: Discharge of electricity originating from high thunderstorms
ice age: ?
greenhouse effect: Atmospheric heating caused by solar radiation being readily transmitted inward through the earth's atmosphere but longwave radiation less readily trasmitted outward, due to absorption by CO₂, methane and other trace gases in the atmosphere

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