Energy DensityThe amount of energy per unit volume. The energy density affects, and is affected by, the expansion or contraction of the universe.
Energy DissipatorA device constructed in a waterway to reduce the kinetic energy of fast flowing water. See stilling basin.
Energy EfficiencyUsing less energy to achieve the same outcome. For example, better insulation would enable a home to stay warm utilizing less energy.
Energy Efficiency Ratio (EER)The measure of the instantaneous energy efficiency of room air conditioners; the cooling capacity in Btu/hr divided by the watts of power consumed at a…
Energy Efficient MortgagesA type of home mortgage that takes into account the energy savings of a home that has cost-effective energy saving improvements that will reduce energy…
Energy End-Use SectorsMajor energy consuming sectors of the economy. The Commercial Sector includes commercial buildings and private companies.
Energy Facility Siting Council (EFSC)In Oregon, a seven-member council that coordinates and approves siting for most large power plants, transmission lines and pipelines.
Energy Factor (EF)The measure of overall efficiency for a variety of appliances. For water heaters, the energy factor is based on three factors: 1) the recovery efficiency…
Energy Guide LabelsThe labels placed on appliances to enable consumers to compare appliance energy efficiency and energy consumption under specified test conditions as…
Energy Helicity IndexAn index that incorporates vertical shear and instability, designed for the purpose of forecasting supercell thunderstorms
Energy IntensityThe relative extent that energy is required for a process.
Energy Policy Act (EPACT)Comprehensive federal legislation enacted in 1992 that is resulting in fundamental changes in the electric utility industry by promoting competion in…
Energy Policy Act of 1992Passed by Congress to enhance U.S. energy security by requiring federal, state, and alternative fuel provider fleets to implement petroleum-reduction…
Energy Policy Act of 1992 (EPAct)A comprehensive legislative package that mandates and encourages energy efficiency standards, alternative fuel use, and the development of renewable…
Energy qualityAbility of a form of energy to do useful work. High-temperature heat and the chemical energy in fossil fuels and nuclear fuels are concentrated high…
Energy Security Act of 1980Legislation authorizing a U.S. biomass and alcohol fuel program, and that authorized loan guarantees and price guarantees and purchase agreements for…
Energy Service Company (ESCO)A company that specializes in undertaking energy efficiency measures under a contractual arrangement whereby the ESCO shares the value of energy savings…
Energy sourceThe primary source that provides the power that is converted to electricity through chemical, mechanical, or other means.
Energy SpectrumThe amount of energy emitted at a specific wavelength of light. For example, the Sun emits light at many wavelengths, which can be seen by passing…
Energy StorageThe process of storing, or converting energy from one form to another, for later use; storage devices and systems include batteries, conventional and…
Engineer's LevelA telescope which is attached to a spirit-tube level, all revolving around a vertical axis and is mounted on a tripod.
Engineering Change Request (ECR)A method of formally requesting that a change be made to the infrastructure. This change can be to a particular instrument, data system, data process…
Engineering Work Request (EWR)Used to request engineering resources, as soon as possible, when operational, science, or engineering needs require a quick engineering response where no…
EngraftmentThe process in which transplanted stem cells or bone marrow cells migrate to the bone marrow and begin producing healthy red blood cells, white blood…
Enhanced Greenhouse EffectThe concept that the natural greenhouse effect has been enhanced by anthropogenic emissions of greenhouse gases.
Enhanced oil recoveryRemoval of some of the heavy oil left in an oil well after primary and secondary recovery. See primary oil recovery, secondary oil recovery.
Enhanced VA pattern seen on satellite infrared photographs of thunderstorms, in which a thunderstorm anvil exhibits a V-shaped region of colder cloud tops extending…
Enhanced Wording1. An option used by the SPC in tornado and severe thunderstorm watches when the potential for strong/violent tornadoes, or unusually widespread damaging…
EnhancementImprovement of a facility beyond its originally designed purpose or condition.
Enhancement flowImproved flows that result in better stream conditions for aquatic, terrestrial, and other resources.
enhancer1. A substance or object that increases a chemical activity or a physiological process. 2.
enolpyruvyl-shikimate-3-phosphate synthase(Abbreviation EPSP synthase or EPSPS). An enzyme produced by virtually all plants, which is essential for normal metabolism, and for the biosynthesis of…
ENSEMBLEA collection of numerical model results that show slightly different possible outcomes.
Ensemble ForecastMultiple predictions from an ensemble of slightly different initial conditions and/or various versions of models.
Ensemble Hydrologic ForecastingA process whereby a continuous hydrologic model is successively executed several times for the same forecast period by use of varied data input scenarios…
EnsemblesReference to a set of computer models run under the concept of Ensemble Forecasting: multiple predictions from an ensemble of models with slightly…
Ensign valveEarliest type of Reclamation needle valve (named after Reclamation's chief electrical engineer), operated by water pressure from the forebay, and mounted…
ENSOAbbreviation for El Niño-Southern Oscillation, a reference to the state of the Southern Oscillation.
ENSO Diagnostic DiscussionThe CPC issues the ENSO Diagnostic Discussion around the middle of the month. The discussion addresses the current oceanic and atmospheric conditions in…
Enteric fermentationA digestive process by which carbohydrates are broken down by microorganisms into simple molecules for absorption into the bloodstream of an animal.
enterotoxinA bacterial protein that, following release into the intestine, causes cramps, diarrhoea and nausea.
EnthalpyA thermodynamic property of a substance, defined as the sum of its internal energy plus the pressure of the substance times its volume, divided by the…
EntrainTo trap bubbles in water either mechanically through turbulence or chemically through a reaction.
Entrained Bed GasifierA gasifier in which the feedstock (fuel) is suspended by the movement of gas to move it through the gasifier.
EntrainmentThe incorporation of fish, eggs, larvae, and other plankton with intake water flow entering and passing through a cooling water intake structure and into…
Entrainment ZoneA shallow region at the top of a convective boundary layer where fluid is entrained into the growing boundary layer from the overlying fluid by the…
Entrance RegionThe region upstream from a wind speed maximum in a jet stream (jet max), in which air is approaching (entering) the region of maximum winds, and therefore…
EntropyA measure of the unavailable or unusable energy in a system; energy that cannot be converted to another form.
EntryAn application to acquire title to public lands.
enucleated ovumEgg cell from which the nucleus has been removed, usually as a preparatory step for nuclear transfer.
EnvironmentAll the natural and living things around us. The earth, air, weather, plants, and animals all make up our environment.
Environment CanadaThe Canadian federal government department responsible for issuing weather forecasts and weather warnings in Canada.
Environmental analysisSystematic process for consideration of environment factors in land management actions.
Environmental Assessment (EA)A public document that analyzes a proposed federal action for the possibility of significant environmental impacts.
Environmental Impact Statement (EIS)A comprehensive study of likely environmental impacts resulting from major federally-assisted projects; statements are required by the National…
Environmental JusticeIs based on the principle that all people have a right to be protected from environmental pollution and to live in and enjoy a clean and healthful…
Environmental Lapse RateThe rate of decrease of air temperature with height, usually measured with a radiosonde.
Environmental mediaSoil, water, air, biota, or any other parts of the environment that can contain contaminants.
Environmental Protection Agency (EPA)Environmental Protection Agency (EPA) was established as an independent agency on December 2, 1970 during President Nixon's term in office.
Environmental Resource Inventory (ERI)A listing and description of natural resources and general environmental characteristics of a given geographic area.
Enzymatic hydrolysisA process by which enzymes (biological catalysts) are used to break down starch or cellulose into sugar.
enzymeA protein that speeds up chemical reactions in the body.
enzyme bioreactorA reactor in which a chemical conversion reaction is catalysed by an enzyme.
Enzyme Commission number(Abbreviation: EC number). Systematic label which identifies an enzyme in the technical literature.
enzyme electrodeA type of biosensor, in which an enzyme is immobilized onto the surface of an electrode.
enzyme immunoassayA range of immunoassay techniques employing enzymes, which includes ELISA.
enzyme kineticsThe quantitative characteristics of enzyme reactions.
enzyme stabilizationMaintaining the active conformation of an enzyme. This can be achieved in vitro by providing the appropriate chemical environment and cofactors.
EnzymesProteins that control the various steps in all chemical reactions.
EolianRefers to the processes of wind erosion, transport, and deposition. For example, sand dunes are landforms produced by eolian processes in arid…
EP ToxicityA test defined by the federal Environmental Protection Agency to check a substance for the presence of arsenic, barium, cadmium, chromium, lead, mercury…
Ephemeral allotmentA BLM grazing allotment in areas of the Hot Desert Biome (Region) that do not consistently produce enough forage to sustain a livestock operation, but…
Ephemeral creekA creek or stream that flows briefly only in direct response to precipitation and whose channel is above the water table. See intermittent stream.
Ephemeral streamA stream that flows only after a storm or during snowmelt and whose channel is, at all times, above the water table; groundwater is not a source of water…
EpiblastGives rise to the ectoderm and mesoderm. The mesoderm then displaces the hypoblast cells and forms the entodermal cell layer on its inner surface.
EpicenterFocal point on the earth's surface directly above the origin of a seismic disturbance.
epicotylThe upper portion of the axis of a plant embryo or seedling, above the cotyledons.
Epidermal growth factor (EGF)A cell messenger protein that has effects including stimulation of epidermal development, in newborn animals it hastens eyelid-opening and tooth-eruption
epidermis(ep-i-DER-mis) The upper or outer layer of the two main layers of tissue that make up the skin.
epigenesisDescribes the developmental process whereby each successive stage of normal development is built up on the foundations created by the preceding stages of…
epigenetic variationNon-hereditary and reversible variation; often the result of a change in gene expression due to methylation of DNA.
epinastyA process by which the growth of branches or petioles is abnormally pointing downward.
epiphyteA plant that grows upon another plant, but is neither parasitic on it nor rooted in the ground.
episomeA genetic extrachromosomal element (e.g. the F factor in Escherichia coli) which replicates within a cell independently of the chromosome and is able to…