Glossary - Environmental Science - page 324

equinox The time when the sun crosses the ecliptic plane of Earth's equator, making day and night equal
length. It occurs twice a year, on or about March 21 and September 23.
erosion The process of soil and sediment being transported from a location via wind or water.
eutrophication The process of excess nitrogen or phosphorous entering an aquatic system, leading to an ex-
cessive growth of phytoplankton, algae, and other plants, which commonly consume the system's available
oxygen.
evaporation Phase change of liquid to gas, from the surface of water.
even-aged Term used to describe trees that are planted and then harvested at the same time, so they are all the
same age.
evolution The change of a population's genetic makeup through generations.
exponential growth Growth at a constant rate. If population increases by a fixed percentage per unit time, the
gross rate of population growth increases.
extinct volcano A volcano that is not erupting and most likely will not erupt at any point again.
extirpation The destruction or disappearance of a population from a particular area while populations remain
elsewhere.
Ferrel air circulation cell The air circulation cell that causes the temperate convection current (between the
tropical convection current and polar convection current).
focus The location from which an earthquake originates within the Earth.
food chain A simple path of energy flow from the producer to the various consumers.
food web Multiple intertwined food chains in which energy from multiple producers flows though many levels
of consumers and finally through the decomposers.
forestry The practice of balancing humans' use of wood products with the importance of forests as ecosystems.
fossil fuel Energy sources formed by the decomposition of plants and animals that have been compressed and
heated in the Earth's crust for millions of years; they include coal, crude oil, and natural gas.
Freon The DuPont trade name for chlorofluorocarbons (CFCs)
freshwater Naturally occurring water on the Earth's surface that is low in concentrations of dissolved salts and
other dissolved particles. Freshwater is primarily found in glaciers, ice sheets, and ice caps, with a relatively
small amount found in groundwater, ponds, lakes, rivers, and streams.
generalists Organisms that have a broad tolerance and can adjust to different situations.
genetic engineering The creation of new organisms by changing segments of DNA; also called genetic modi-
fication.
genetic pollution The unintended spread of altered genetic information from genetically engineered organisms
to natural organisms.
genetically modified organisms (GMOs) Organisms that have altered DNA as a result of genetic engineering.
geologic time scale The 4.54 billion years of Earth's history.