Glossary of Terms: A
- Abiotic - Non-living thing. Usually refers
to the physical and chemical components of an organism's environment.
Also called inorganic.
Ablation - Surface removal of ice or snow from
a glacier or snowfield by melting, sublimation,
Zone - Region in a glacier where
there is a surface net removal of snow and/or ice by melting, sublimation,
Abrasion - Physical wearing and grinding of
a surface through friction and impact by material carried
in air, water, or ice.
Humidity - Measurement of atmospheric humidity.
Absolute humidity is the mass of
water vapor in a given volume o
air (this measurement is not influenced by the
mass of the air). Normally expressed in grams of
water vapor per cubic meter of atmosphere at a
Zero - Temperature of
-273.15° Celsius. At this temperature atomic motion
Absorption - (1) Process of taking in and being
made part of an existing amount of matter. (2) Interception of electromagnetic
radiation or sound.
Absorption (Atmospheric) - Atmospheric absorption
is defined as a process in which solar
radiation is retained by a substance and
converted into heat
energy. The creation of heat energy also
causes the substance to emit its own radiation.
In general, the absorption of solar radiation by
substances in the Earth's atmosphere results
in temperatures that get no higher than 1800° Celsius.
According to Wien's
Law, bodies with temperatures at this level
or lower would emit their radiation in the longwave
Space - Geographic model or representation
of the real world. For example, maps and globes
are abstractions of the real world or concrete
Fan - Fan shaped accumulation of sediment
from rivers that is deposited at the base of a submarine
canyon within an ocean
Plain - Another name for ocean
Acclimation - Slow adjustment of an organism to
new conditions in its environment.
Accretion - The growth of the continental masses
time via the addition of marine sediments.
These sediments are added on to the edges of the
continents through tectonic collision
with other oceanic or continental
Accumulation - Surface addition of snow to
a glacier or snowfield.
Zone - (1) Region in a glacier where
there is a surface net addition of snow. (2) Part of a hillslope that has
a net gain of material leading to a progressive
raising of the slope's surface.
Acid - (1) Substance having a pH less
than 7. (2) Substance that releases hydrogen
Deposition - Atmospheric deposition
of acids in solid or
liquid form on the Earth's surface. Also see acid
Acidic - Any substance with a pH below
Solution - Any water solution that is acidic (pH
less than 7) or has more hydrogen ions (H+) than
hydroxide ions (OH-). Also see basic
solution and neutral
Precipitation - Atmospheric precipitation with
a pH less
than 5.6. Normal pH of precipitation is 5.6.
Rain - Rain with
a pH less than 5.6. Normal pH of precipitation
Shock - A sudden acidification of runoff waters
from the spring melting of accumulated snow in
the middle latitudes because of the winter deposition
of acidic precipitation.
Actinomycetes - Group of filamentous microorganisms
that are intermediate between bacteria and fungi.
Layer - Upper zone of soil in
higher latitude locations that experiences daily
and seasonal freeze-thaw cycles.
Remote Sensing - Form of remote
sensing where the sensor provides
its own source of electromagnetic
radiation to illuminate the object
understudy. Radar is an example of an active
remote sensing device.
Evapotranspiration - Is the amount of water that is
actually removed from a surface due to the processes
of evaporation and transpiration.
Mixing Ratio - Another term used to describe mixing
Adaptation - (1) Evolutionary adaptation - a
genetically based characteristic expressed by a
living organism. Particular adaptations found in populations become
frequent and dominant if they enhance an individual's
ability to survive in the environment. (2) Physiological adaptation -
change in an organism's physiology as a result
of exposure to some environmental condition.
Radiation - The evolution of
a number of new species from
one or a few ancestor species over many thousands
or millions of years. Normally occurs after a mass
extinction creates a number of vacant ecological
niches or when a radical change in the
environment produces new ecological niches.
Adiabatic - A process in which heat does
not enter or leave a system. In the atmospheric
sciences, adiabatic processes are often used to
model internal energy changes in rising and descending
parcels of air in the atmosphere.
When a parcel of air rises it expands because of
a reduction in pressure.
If no other non-adiabatic processes occur (like
condensation, evaporation and radiation), expansion
causes the parcel of air to cool at a set rate
of 0.98° Celsius per 100 meters. The opposite
occurs when a parcel of air descends in the atmosphere.
The air in a descending parcel becomes compressed.
Compression causes the temperature within the parcel
to increase at a rate of 0.98° Celsius per
Cooling - The cooling of a rising parcel
of air due to adiabatic processes.
Advection - Process that involves the transfer
of mass and heat energy by
means of horizontal motions through a fluid substance like air or water.
Also see convection.
Fog - Fog generated
when winds flow over a surface with a different
temperature. Two types of advection fog exist.
When warm air flows over a cold surface it can
produce fog through contact cooling. Cold air blowing
over a warm moist surface produces a form of advection
fog know as evaporation
Aeolian - Geomorphic process involving wind.
Alternative spelling eolian.
Landform - Is a landform formed from the erosion or deposition of weathered surface materials by wind.
This includes landforms with some of the following
geomorphic features: sand dunes, deflation
hollows, and desert
pavement. Alternative spelling eolian
Photography - Form of remote
sensing that captures images of objects
using photographic cameras and film from platforms
in the atmosphere.
Aerobic - (1) Presence of molecular oxygen. (2) Occurring only in the presence
of molecular oxygen. (3) Growing in the presence of
Aftershock - Smaller earth tremors that occur
seconds to weeks after a major earthquake event.
Aggradation - Readjustment of the stream
profile where the stream
channel is raised by the deposition of bed
Agronomy - Field of science that studies phenomena
related to agriculture.
A Horizon - Soil horizon normally
found below the O
horizon and above the B
horizon. This layer is characterized by
the following two features: (1) A layer in which humus and
other organic materials are mixed with mineral
particles. (2) A zone of translocation from
which eluviation has
removed finer particles and soluble substances.
Air Mass - A body of air whose temperature and humidity characteristics
remain relatively constant over a horizontal distance
of hundreds to thousands of kilometers. Air masses
develop their climatic characteristics by remaining
stationary over a source
region for a number of days. Air masses
are classified according to their temperature and
Pollution - Toxification of the atmosphere
through the addition of one or more harmful substances
in the air. Substance must be in concentrations
high enough to be hazardous to humans, other animals,
vegetation, or materials. Also see primary
pollutant and secondary
Pressure - See atmospheric
Albedo - Is the reflectivity of
Low - Subpolar
low pressure system found near the
Aleutian Islands. Most developed during the
winter season. This large-scale pressure system
spawns mid-latitude cyclones.
Alfisols - Soil order
(type) of the United
States Natural Resources Conservation Service Soil
Classification System. Soil associated
with forest vegetation. Upper layers of this soil
are relatively rich in organic
matter. Whitish layer found in the A
horizon because of eluviation. Illuvial layer
forms in the B horizon.
Algae - A simple photosynthetic plant that
usually lives in moist or aquatic environments.
The bodies of algae can be unicellular or multicellular
Species - Species that
is not naturally found in a region.
Alkaline - (1) Having a pH greater
than 7. (2) Substance that releases hydroxyl
Allele - Alternative forms of a gene.
Each form produces a unique inheritable characteristic.
Allelopathy - A particular form of amensalism found
In this interaction,
one species produces
and releases of chemical substances that inhibit
the growth of another species.
Succession - A succession caused
by a change in environmental conditions
that is unrelated to the activities of the developing plant community.
Speciation - The evolution of
a new species because
of the isolation of a small group of individuals
from the other members of a population.
Allophane - Hydrated aluminosilicate substance
ordinarily found associated with clay minerals.
Fan - Large fan shaped terrestrial deposit
of alluvial sediment
on which a braided
stream flows over. Form as stream
load is deposited because of a reduction
in the velocity of stream
Terraces - Flat elevated benches composed
of unconsolidated alluvium found
either side of a stream
channel. Formed when a stream down cuts
into its floodplain.
Alluvium - Sediment that
originates from a stream.
Particle - Particle of matter that
is positively charged. This particle consists of
two neutrons and two protons and
is emitted as a form of radioactivity from the
nuclei of some radioisotopes.
Also see beta
particle and gamma
Glacier - Small glacier that
occupies a U-shaped valley on a mountain. Also
called a mountain glacier.
Permafrost - Form of permafrost that
exists at high altitudes in mountainous environments.
Tundra - High altitude biome dominated
by a few species of dwarf shrubs,
a few grasses, sedges, lichens,
and mosses. Productivity is
low in this biome because of the extremes of climate.
Quite similar to tundra.
Alternative Hypothesis (H1) - Is a hypothesis that
has been suggested because it is believed to be false or because it is to be used as a starting point for scientific argument. Used in statistical testing to organize arguments.
Altitude - Vertical distance above sea-level.
Clouds - Middle altitude cloud that
is colored from white to gray. This cloud is composed
of a mixture of water droplets and ice crystals.
It appears in the atmosphere as layers or patches
that are well rounded and commonly wavelike. Found
in an altitude range from 2,000 to 8,000 meters.
Clouds - Gray-looking middle altitude cloud that
is composed of water droplets and ice crystals.
Appears in the atmosphere as dense sheet like layer.
Can be recognized from stratus
clouds by the fact that you can see the
Sun through it. Found in an altitude range from
2,000 to 8,000 meters.
Amensalism - Interspecific interaction where one species suffers in terms of fitness,
while the fitness of the other species does not
change. See allelopathy.
Acid - Organic nitrogen
containing acids which
are used to construct proteins.
Ammonia - Chemical compound composed of nitrogen
and hydrogen (NH3). Component of the nitrogen
cycle. Immediately released from organic
matter upon decomposition.
Ammonium - Chemical compound composed of nitrogen
and hydrogen (NH4). Component of the nitrogen
cycle. Product of organic matter decomposition.
Can be fixed to clay minerals and later exchanged.
Amphibian - Group of vertebrate animals that
can inhabit both terrestrial and aquatic habitats.
This group of animals consists of frogs, newts,
and salamanders. These organisms live at the land/water
interface and spend most of their life in water.
Descended from fish and ancestors to reptiles.
Amphibole - A group of double chained inosilicate minerals whose
basic chemical unit is the tetrahedron (SiO
). They are common rock forming minerals and are found in most igneous and metamorphic rocks.
They form at low temperatures with the presence of water in the crystallization
environment. There are about 60 recognized mineral types in this group.
Anaerobic - (1) Absence of molecular oxygen. (2) Occurring only in the absence
of molecular oxygen. (3) Growing in the absence of molecular
Andesite - An extrusive igneous rock that develops from a
magma that is chemically between felsic and mafic and
whose mineral crystals
Andisols - Soil order
(type) of the United
States Department of Agriculture Comprehensive
Soil Classification System. These soils
develop from parent materials that
are volcanic in
Anemometer - Mechanical instrument used to measure wind speed.
These instruments commonly employee three methods
to measure this phenomenon: 1) A device with three
or four open cups attached to a rotating spinal.
The speed of rotation is then converted into a
measurement of wind speed; 2) A pressure plate
that measures the force exerted by the moving wind
at right angles; 3) An instrument consisting of
a heated-wire where electrical resistance (temperature
of the wire) is adjusted to account for heat lost
by air flow. The faster the wind the greater the
heat loss and thus the more energy that is required
to keep the wire at a constant temperature. As
a result, wind speed is measured through the drain
of electrical current.
Barometer - Barometer that
measures atmospheric pressure via
the expansion and contraction of a sealed hollow
cell which is partially depleted of air.
Angiosperms - Group of vascular plants who
encase their seeds in a mature ovary or fruit.
of Incidence - Angle at which the Sun's rays or insolation strike
the Earth's surface. If the Sun is positioned directly
over head or 90° from the horizon, the incoming
insolation strikes the surface of the Earth at
right angles and is most intense.
of Repose - Measurement commonly used in civil
engineering. It is the maximum angle at which a
material can be inclined without failing. Geomorpologist
use this measurement for determining the stability
of slope to mass
Animal - Organisms that belong to the kingdom Animalia.
General characteristics of these organisms include: eukaryotic cell
and a complex nervous system. This group of life
includes organisms like sponges, jellyfishes, arthropods
(insects, shrimp, and lobsters), mollusks (snails,
clams, oysters, and octopuses), fish, amphibians
(frogs, toads, and salamanders), reptiles (turtles,
lizards, alligators, crocodiles, snakes), birds,
and mammals (kangaroos, bats, cats, rabbits, elephants,
whales, porpoises, monkeys, apes, and humans).
Animalia - Group, at the kingdom level,
in the classification of life. Multicellular organisms
that have a eukaryotic cell
and a complex nervous system.
Anion - An ion carrying
a negative atomic charge.
Plant - Plant species that completes its
life in one growing season.
Circle - Latitude of
66.5° South. The northern limit of the area
of the Earth that experiences 24 hours of darkness
or 24 hours of day at least one day during the
High - A region of high
pressure that occupies central Antarctic
throughout the year. This pressure system is
responsible for very cold temperatures and
extremely low humidity.
Anticline - A fold in rock layers that forms an arch.
Anticyclone - An atmospheric pressure
system consisting of an area of high
pressure and outward circular surface wind
flow. In the Northern Hemisphere winds from an
anticyclone blow clockwise, while Southern Hemisphere
systems blow counterclockwise.
Aphelion - The point in the Earth's
orbit when it is farthest from the Sun. This distance is bout 152.1
million kilometers (94.5 million miles). Aphelion occurs on the 3rd
or 4th of July. Compare with perihelion.
Physical Geography - The field of Applied Physical Geography
uses theoretical information from the various fields
of Physical Geography to
manage and solve problems related to natural phenomena
found in the real world.
Aquatic - With reference to water.
Aquiclude - Rock formations
that are impermeable to groundwater water.
Aquifer - Rock formations
that store groundwater water.
Recharge Area - Surface area that provides water
for an aquifer.
Archaea - Is a group of recently discovered
organisms that resemble bacteria.
However, these organisms are biochemically and
genetically very different from bacteria. Some
species of the domain Archaea live in the
most extreme environments found on the Earth.
Archaebacteria - Term used to describe organisms
that belong to the biological domain Archaea.
Archean - Geologic eon that
occurred from 2500 to 3800 million years ago. During
this time period, the first single-celled prokaryote organisms evolved and developed.
Archipelago - A group of islands that have an
arc shaped distribution. These islands are usually
of volcanic origin
and are associated with subduction
Studies Tradition - Academic tradition in modern Geography that
investigates an area on the Earth from a geographic
perspective at either the local, regional, or global
Arête - Sharp topographic ridge that separates cirques on
a mountain that is or has been glaciated.
Arkose - A type of sedimentary sandstone that
contains a large quantity of weathered feldspar grains.
This type of sedimentary rock forms in arid conditions.
Aridisols - Soil order
(type) of the United
States Natural Resources Conservation Service Soil
Classification System. Aridisols are commonly
found in dry environments that are low in organic
matter and rich in deposited salts.
Water - Groundwater that
is confined by two impermeable layers beneath the
Well - A well where the water rises and
flows out to the surface because of hydrostatic
Circle - Latitude of
66.5° North. The southern limit of the area
of the Earth that experiences 24 hours of darkness
or 24 hours of day at least one day during the
Reproduction - Any process of reproduction that
does not involve the fusion of gametes.
Assimilation - (1) Absorption and creation of
food resources. (2) Organic metabolic products
of food digestion. Usually the various organic
constituents of the organism.
Asthenosphere - Zone in the Earth's mantle that
exhibits plastic properties. Located below the lithosphere at
between 100 and 200 kilometers.
Astronomy - Field of knowledge that studies
the nature, motion, origin, and constitution of
Atmosphere - The atmosphere is the vast gaseous
envelope of air that surrounds the Earth. Its boundaries
are not easily defined. The atmosphere contains
a complex system of gases and suspended particles
that behave in many ways like fluids. Many of its
constituents are derived from the Earth by way
of chemical and biochemical reactions.
Pressure - Weight of the atmosphere on
a surface. At sea-level,
the average atmospheric pressure is 1013.25 millibars.
Pressure is measured by a device called a barometer.
Stability - Relative stability of parcels of
air relative to the atmosphere that surrounds them. Three conditions
are generally described: stable, unstable,
Atoll - A ring shaped reef composed
largely of coral.
These features are quite common in the tropical
waters of the Pacific Ocean.
Atom - Smallest unit of an element that
still maintains its chemical characteristics.
Energy - Energy released
from an atomic nucleus because of a change in
its subatomic mass.
Mass Number - Combined number of an atom's protons and neutrons.
Number - Number of protons in
the nucleus of
Weight - Combined weight of an atom's electrons, protons,
Attribute (System) - See system attribute.
Aurora - Multicolored lights that appear
in the upper atmosphere (ionosphere)
over the polar regions and visible from locations
in the middle and high latitudes. Caused by the
interaction of solar
wind with oxygen and nitrogen gas in the
atmosphere. Aurora in the Northern Hemisphere are
called aurora borelis and aurora
australis in the Southern Hemisphere.
Succession - Succession where
the plant community causes
the environment to
change and this modification drives the succession.
Autotroph - An organism that produces food
molecules inorganically by
using a light or chemical based sources of external
energy. This organism does not require outside
sources of organic food energy for survival. Also
see chemical autotrophs and photosynthetic
Equinox - One of two days during the year
when the declination of
the Sun is at the equator. The autumnal equinox
denotes the first day of the fall season. For the
Northern Hemisphere, the date of autumnal equinox
on either September 22 or 23 (changes yearly).
March 20 or 21 is the date of the autumnal equinox
in the Southern Hemisphere. During the autumnal
equinox, all locations on the Earth (except the
poles) experience equal (12 hour) day and night.
Water - Portion of the capillary
water that is available for plant root
Global Temperature - Average annual temperature of
the Earth's entire surface atmosphere.
Azimuth - A system that measures direction
clockwise from North over 360°.
Azimuthal Projection - Is a two-dimensional map projection where distances and directions are properly depicted from the center point found on a map. This projection has distortion in terms of the shape and size of objects found on this type of map.
Azimuth System - System for determining direction that uses azimuth measurements.
Soil - A soil without
High - See Bermuda
M. (2010). "Glossary of Terms: A". In: Glossary of Terms, www.our-planet-earth.net. Date