Local emergency operations plan (LEOP)A general planning document, required by law, that describes the responsibilities and actions to be performed in the event of an emergency and/or disaster…
Local emergency planning committee (LEPC)A committee made up of local officials, citizens, and industry representatives charged with development and maintenance of emergency response plans for…
Local Flood Warning System (LWFS)(LWFS)A general designator for a network of stream and rain gages implemented by a community or local government to monitor hydrologic events as they occur.
Local FloodingFlooding conditions over a relatively limited (localized) area.
Local GovernmentA legally-established unit of government at a level below state or territory government, including but not limited to, county, city, town, or village.
Local GroupA small cluster of more than 30 galaxies "near" to our galaxy, including the Andromeda galaxy and the Magellanic Clouds.
Local officials/authoritiesThe personnel authorized by election or job title to carry out the operation, planning, mitigation, preparedness, response, and recovery functions of the…
Local organizationThe local government agency or office having the principal or lead role in emergency planning and preparedness.
Local runoffWater running off a local area, such as rainfall draining into a nearby creek.
Local Solar TimeA system of astronomical time in which the sun crosses the true north-south meridian at 12 noon, and which differs from local time according to longitude…
LocalizeDetermination of the original position (locus) of a gene or other marker on a chromosome.
Locatable MineralsMinerals or materials subject to disposal and development through the Mining Law of 1872 (as amended).
Location Efficient MortgageA lending program that allows homebuyers to borrow more money based on the transportation cost savings of living near mass transit.
Locational installed capacityInstalled capacity in a specific location (e.g., New York City), rather than in a broader area (e.g., anywhere in New York State).
Locational marginal priceThe market-clearing price for electricity at the location the energy is delivered or received.
LockoutLockout means a labor dispute involving a work stoppage, wherein an employer withholds work from its employees in order to gain a concession from them.
Lockout deviceA device that utilizes a positive means such as a lock, either key or combination type, to hold an energy isolating device in the safe position and…
locus(LOH-kuss) Specific place where something is located or occurs. It may refer to a specific place on the body (such as an acupuncture point) or the place…
Locus (pl. loci)The position on a chromosome of a gene or other chromosome marker; also, the DNA at that position.
LOD scoreThe logarithm of the odds of linkage between two loci. Used to measure the statistical support for linkage.
LODEA mineralized ledge, vein or mineral deposit in place.
Lode mining claimA claim based on the presumption that the valuable mineral is a part of a bed-rock lode, vein, stockwork, stratum, or intrusion and is not dominantly a…
LoessA group of windblown soils, largely comprising silt, weakly cemented by calcite.
LoessialMedium-textured materials (usually silt or very fine sand) transported and deposited by wind action.
LoftingA pattern of plume dispersion in a stable boundary layer topped by a neutral layer, in which the upper part of the plume disperses upward while the lower…
Log and Safety BoomA net-like device installed in a reservoir, upstream of the principal spillway, to prevent logs, debris and boaters from entering a water discharge…
Log boomA floating structure used to protect the face of a dam by deflecting floating material and waves away from the dam.
Log chokerA length of cable or chain that is wrapped around a log or harvested tree to secure the log to the winch cable of a skidder or to an overhead cable…
Log LawIn reference to a wind energy conversion system, the wind speed profile in which wind speeds increase with the logarithmic of the height of the wind…
Logbook (operating log)A dated, written record of performed operation and maintenance items or observations pertinent to a structure.
Logging residuesThe unused portion of wood and bark left on the ground after harvesting merchantable wood.
longA term signifying ownership of securities. "I am long 100 XYZ," means that the speaker owns 100 shares of XYZ.
long interspersed nuclear element(Abbreviation: LINE). Families of common DNA elements, of average length 6.5 kb, which are dispersed at numerous locations within the genome.
long templateA DNA strand, synthesized during PCR, which has a primer sequence at one end but is extended beyond the site that is complementary to the second primer at…
Long Term RetentionRetention of data for 5 years to satisfy requirements for local studies and to support litigation.
Long Term Storage DamsReservoirs used for recreational use or storage of irrigation, municipal or industrial water.
long terminal repeat(Abbreviation: LTR). A characteristic sequence of nucleotides that occurs at each end of a retrovirus element that has become integrated into the host…
Long TonA unit that equals 20 long hundredweight or 2,240 pounds. Used mainly in England.
long-day plantPlants requiring a period of short nights before the switch from vegetative to reproductive growth can be initiated. See: Short-day plant.
Long-Range Restriction MappingRestriction enzymes are proteins that cut DNA at precise locations. Restriction maps depict the chromosomal positions of restriction-enzyme cutting sites.
Long-term productivityThe capacity of a site to support forest ecosystems over generations of humans and trees as measured against some defined reference.
Long-term self-renewalThe ability of stem cells to renew themselves by dividing into the same non-specialized cell type over long periods (many months to years) depending on…
Long-throated flumesLong-throated flumes control discharge rate in a throat that is long enough to cause nearly parallel flow lines in the region of flow control.
LongitudeThe location east or west in reference to the Prime Meridian, which is designated as zero (0) degrees longitude.
LongitudinalPertaining to or extending along the long axis, or length, of a structure. Lengthwise. See transverse.
longwave net radiationThe difference between upwelling and downwelling broadband longwave radiation.
longwave radianceThe rate at which light energy in the longwave portion of the spectrum is emitted in a particular direction per unit of projected surface area…
Longwave RadiationA term used to describe the infrared energy emitted by the earth and atmosphere at wavelengths between about 5 and 25 micrometers.
Longwave TroughA trough in the prevailing westerly flow aloft which is characterized by large length and (usually) long duration.
loop bioreactorFermenters in which material is cycled between a bulk tank and a smaller tank or loop of pipes.
Loop flowUnintended or unscheduled flow of electricity through a line or system.
Loop Prominence System(abbrev. LPS) In solar-terrestrial terms, a system of loop prominences associated with major flares.
LoopingA pattern of plume dispersion in an unstable atmosphere, in which the plume undergoes marked vertical oscillations as it is alternately affected by rising…
Loose Fill InsulationInsulation made from rockwool fibers, fiberglass, cellulose fiber, vermiculite or perlite minerals, and composed of loose fibers or granules can be…
Loose yardsMeasurement of soil or rock after it has been loosened by digging or blasting.
LoranLong Range Navigation, a system of long range navigation whereby latitude and longitude are determined from the time displacement of radio signals from…
Losing streamA stream or reach that contributes water to a zone of saturation.
Loss of Load Probability (LOLP)(LOLP)A measure of the probability that a system demand will exceed capacity during a given period; often expressed as the estimated number of days over a long…
LossesEnergy (kilowatt-hours) and power (kilowatts) lost in the operation of an electric system, principally as waste heat in electrical conductors and…
Losses (Energy)A general term applied to the energy that is converted to a form that can not be effectively used (lost) during the operation of an energy producing…
Lot Areaarea is the total square footage of horizontal area included within the property lines.
LoticMoving water systems such as streams and rivers.
Lotic SystemA flowing body of fresh water, such as a river or stream. Compare lentic system.
LowA region of low pressure, marked as "L" on a weather map. A low center is usually accompanied by precipitation, extensive cloudiness, and moderate winds.
Low Btu GasA fuel gas with a heating value between 90 and 200 Btu per cubic foot.
Low damA dam up to 100 feet high. See medium-height dam and high dam.
Low density materialA material having a low weight per unit volume either as it occurs in its natural state or after compacting it, such as loess with a density of 80 pounds…
Low Flush ToiletA toilet that uses less water than a standard one during flushing, for the purpose of conserving water resources.
Low Frequency(abbrev. LF) The portion of the radio frequency spectrum from 30 to 300 kHz.
Low hazardA downstream hazard classification for dams in which no lives are in jeopardy and minimal economic loss (undeveloped agriculture, occasional uninhabited…
Low Impact Development (LID)An approach to environmentally friendly land use planning. It includes a suite of landscaping and design techniques that attempt to maintain the natural…
Low Level Jet(abbrev. LLJ)- A region of relatively strong winds in the lower part of the atmosphere.
Low Pressure SystemAn area of a relative pressure minimum that has converging winds and rotates in the same direction as the earth.
Low-e windowsLow-emittance (Low-E) refers to very thin coatings on a window primarily used to reduce heat flow through the window.
Low-Emissivity Windows & (Window) FilmsEnergy-efficient windows that have a coating or film applied to the surface of the glass to reduce heat transfer through the window.
Low-head hydroelectricHydroelectric power that operates with a head of 20 meters (approximately 66 feet) or less.
Low-income populationPersons whose average family income is below the poverty line. The poverty line takes into account family size and age of individuals in the family.
Low-level cloudsLow-level clouds (St, Sc, Ns) Stratus, Stratocumulus, and in some degree, Nimbostratus are low clouds.
Low-level magnetic fieldsFields of force that are generated whenever electric current flows. The sun's average large-scale magnetic field, and the Earth's, exhibit a north and a…
Low-Pressure Sodium LampA type of lamp that produces light from sodium gas contained in a bulb operating at a partial pressure of 0.13 to 1.3 Pascal.
Lower (Net) Heating ValueThe lower or net heat of combustion for a fuel that assumes that all products of combustion are in a gaseous state. (See Net Heating Value below.)
Lower heating valueQuantity of heat liberated by the complete combustion of a unit volume or weight of a fuel assuming that the produced water remains as a vapor and the…
Lower Heating Value (LHV)(LHV)The heating value is the amount of heat released during the combustion of a specific substance, usually a fuel or food.
lower heating value (LLV)(LLV)The heat produced by combusting one unit of a substance, at atmospheric pressure under conditions such that all water in the products remains in the form…