Science terms starting with L

480 terms

LEWP Line Echo Wave Pattern. A bulge in a thunderstorm line producing a wave-shaped "kink" in the line.
LFC An acronym for Level of Free Convection- the level at which a parcel of saturated air becomes warmer than the surrounding air and begins to rise freely.
LFT Lift
LFWS A generic term for any type of Local Flood Warning System.
LGT Light
LGWV Long Wave
LH2O The heat (Btu) needed to vaporize and superheat one pound of water.
LI Lifted Index. A common measure of atmospheric instability. Its value is obtained by computing the temperature that air near the ground would have if it…
library A collection of cells, usually bacteria or yeast, that have been transformed with recombinant vectors carrying DNA inserts from a single species.
License a contract in which the owner of the patent grants another person or company permission to make, use, or sell the patented invention.
Lid (Also called cap.) A region of negative buoyancy below an existing level of free convection (LFC) where energy must be supplied to the parcel to maintain…
LIDAR An instrument similar to a radar but uses a laser to generate light pulses rather than radio waves, generally used to measure aerosol content and particle…
life cycle The sequence of events from a given developmental stage in one generation to the same stage in the following generation.
Life Cycle Cost The sum of all the costs both recurring and nonrecurring, related to a product, structure, system, or service during its life span or specified time…
Life-cycle costing A method of comparing costs of equipment or buildings based on original costs plus all operating and maintenance costs over the useful life of the…
Lifetime (Atmospheric) The lifetime of a greenhouse gas refers to the approximate amount of time it would take for the anthropogenic increment to an atmospheric pollutant…
LIFR Low Instrument Flight Rules
Lift The force that pulls a wind turbine blade, as opposed to drag.
Lift line Horizontal construction joint created when new concrete is placed on previously placed concrete.
Lifted Index (abbrev. LI)- A common measure of atmospheric instability. Its value is obtained by computing the temperature that air near the ground would have if it…
Lifting Condensation Level (LCL) - The level at which a parcel of moist air becomes saturated when it is lifted dry adiabatically.
ligand A small molecule (e.g. activators, substrates and inhibitors of enzyme activity) bound to a protein by non-covalent forces; an ion or a molecule that…
ligase See: DNA ligase.
Ligase (DNA ligase) An enzyme that catalyzes a condensation reaction that links two DNA molecules via the formation of a phosphodiester bond between the 3' hydroxyl and 5'…
ligase chain reaction (Abbreviation: LCR). A technique for the detection and amplification of target DNA sequences.
Ligate The process of joining two or more DNA fragments.
ligate, ligation The joining of two linear double-stranded DNA fragments by the formation of phosphodiester bonds.
Light A pane of glass; a window, or a compartment of a window.
Light Bridge In solar-terrestrial terms, it is observed in white light, a bright tongue or streaks penetra- ting or crossing sunspot umbrae.
Light fixture An electrical device used to create artificial light and/or illumination.
Light pollution Any adverse effect of human-made lighting, such as excessive illumination of night-skies by artificial light.
Light Quality A description of how well people in a lighted space can see to do visual tasks and how visually comfortable they feel in that space.
Light spillage An undesirable condition in which light is cast where it is not wanted. (Also referred to as light trespass.)
Light Trapping The trapping of light inside a semiconductor material by refracting and reflecting the light at critical angles; trapped light will travel further in the…
Light trespass See Light spillage
Light Year The distance light travels in a year: {Distance equals rate times time: 300,000,000 meters per second, times roughly 30 million seconds equals roughly} 9.
Light-duty vehicles Automobiles and light trucks combined.
Light-emitting diode (LED) This very energy efficient lighting technology uses 80 to 90% less energy than conventional lights.
Light-Induced Defects Defects, such as dangling bonds, induced in an amorphous silicon semiconductor upon initial exposure to light.
Lightning (abbrev. LTNG) A visible electrical discharge produced by a thunderstorm. The discharge may occur within or between clouds, between the cloud and air…
Lightning Channel The irregular path through the air along which a lightning discharge occurs. A typical discharge of flash between the ground and the cloud is actually a…
Lightning Discharge The series of electrical processes by which charge is transferred along a channel of high ion density between electrical charge centers of opposite sign.
Lightning Stroke Any of a series of repeated electrical discharges comprising a single lightning discharge (strike).
lignification The thickening and strengthening of a plant cell wall with lignin.
lignin A group of high-molecular-weight amorphous polymers of phenylpropanoid compounds, giving strength to certain tissues. A major component of wood.
lignin pseudo-molecule for modeling The lignin ratio of methoxy groups to phenylpropanoid groups (MeO:C9) is used to calculate an ultimate analysis for the lignin pseudo-molecule.
lignin ratio of MeO to C9 Lignin empirical formulae are based on ratios of methoxy groups to phenylpropanoid groups (MeO:C9).
Lignite A brownish-black coal of low rank with high inherent moisture and volatile matter content, used almost exclusively for electric power generation.
lignocellulose The combination of lignin, hemicellulose and cellulose that forms the structural framework of plant cell walls.
Likely (abbrev. LKLY) In probability of precipitation statements, the equivalent of a 60 or 70 percent chance.
Limb In solar-terrestrial terms, the edge of the solar disk.
Limb Flare In solar-terrestrial terms, a solar flare seen at the edge (Limb) of the sun.
Limestone A sedimentary rock made mostly of the mineral calcite (calcium carbonate). Limestone is usually formed from shells of once-living organisms or other…
Limited Automatic Remote Collector (LARC) An electronic device that interfaces a river or precipitation gage with a telephone line making it possible for remote computers to call a gaging site and…
Limnological conditions Conditions on freshwater lakes.
Limnology Scientific study of the physical characteristics and biology of lakes, ponds, and streams.
line See Groove
Line Echo Wave Pattern (abbrev. LEWP) A radar echo pattern formed when a segment of a line of thunderstorms surges forward at an accelerated rate.
Line item A specified amount in a budget to spend on a particular activity.
Line Loss (or Drop) Electrical energy lost due to inherent inefficiencies in an electrical transmission and distribution system under specific conditions.
line of sight Usually refers to contributions of radiation from the atmosphere along the line-of-sight (path) that an instrument receives.
Line Source An array of pollutant sources along a defined path that can be treated in dispersion models as an aggregate uniform release of pollutants along a line.
Lineage A chart that traces the flow of genetic information from generation to generation.
Lineage surface antigen (Lin) A mixture of monoclonal antibodies that are directed against antigens found on mature hematopoietic cells of different lineages.
Lineament A straight topographic feature of regional extent that is thought to represent crustal structure.
linear phase The growth phase during cell culture when cell number increases arithmetically. The linear phase follows a period of exponential growth.
linearized vector A covalently closed circular DNA vector (typically a plasmid ) which has been opened by restriction digestion to convert it to a linear molecule.
Liner A relatively impermeable barrier designed to keep leachate inside a landfill. Liner materials include plastic and dense clay.
Lining Any protective material used to line the interior surface of a conduit, pipe, or tunnel.
linkage The frequency of coinheritance of a pair of genes and/or genetic markers, which provides a measure of their physical proximity to one another on a…
Linkage disequilibrium See: gametic phase disequilibrium.
linkage equilibrium See: gametic phase equilibrium.
Linkage map See Genetic linkage map.
linked gene, linked marker A gene or marker that is linked to another gene or marker.
Linked genes/markers Genes and/or markers that are so closely associated on the chromosome that they are coinherited in 80% or more of cases.
linker A short, double-stranded oligonucleotide containing a restriction endonuclease recognition site, which is ligated to the ends of a DNA fragment.
Lipase A class of enzymes which break down lipids into their component fatty acids and glycerol.
lipid Fat.
lipofection Delivery into eukaryotic cells of DNA, RNA or other compounds that have been encapsulated in liposomes.
lipopolysaccharide (Abbreviation: LPS). A compound containing lipid bound to a polysaccharide; often a component of microbial cells walls.
liposome (LY-puh-some) A very tiny, fat-like particle that is made in the laboratory. In medicine, liposomes containing drugs or other substances are used in the…
Liposomes Membrane-bound vesicles constructed in the laboratory to transport biological molecules.
Liquefaction Enzymatic digestion (often by alpha-amylase) of gelatinized starch to form lower molecular weight polysaccharides.
Liquefied natural gas (LNG) Natural gas that has been condensed to a liquid by cooling the gas.
Liquefied natural gas (LNG) Reducing the temperature of natural gas to -259 degrees Fahrenheit at atmospheric pressure will convert the gas into a liquid, with a volume about 1/600…
Liquefied petroleum gas (LPG) Ethane, ethylene, propane, propylene, normal butane, butylene, and isobutane produced at refineries or natural gas processing plants, including plants…
Liquid hydrocarbon One of a very large group of chemical compounds composed only of carbon and hydrogen. The largest source of hydrocarbons is petroleum.
Liquid limit (LL) The moisture content corresponding to the arbitrary limit between the liquid and plastic states of consistency of a soil.
liquid medium Culture solution, without a solidifying agent, for in vitro cell growth.
liquid membrane Thin films made up of liquids (as opposed to solids) which are stable in another liquid (usually water).
liquid nitrogen Nitrogen gas condensed to a liquid with a boiling point of about -196 °C. Commonly used as a medium for long-term storage of biological materials.
Liquid Water Equivalent Same as Water Equivalent; the liquid content of solid precipitation that has accumulated on the ground (snow depth).
liquid water path (gm/m^2) A measure of the weight of the liquid water droplets in the atmosphere above a unit surface area on the earth, given in units of kg m-2.
Liquid-Based Solar Heating System A solar heating system that uses a liquid as the heat transfer fluid.
Liquid-To-Air Heat Exchanger A heat exchanger that transfers the heat contained in a liquid heat transfer fluid to air.
Liquid-To-Liquid Heat Exchanger A heat exchanger that transfers heat contained in a liquid heat transfer fluid to another liquid.
List of National System MPAs The List of National System MPAs is the official inventory of all MPAs that have been formally recognized as part of the national system.
Lithic Relating to stone or rock.
Lithic debitage Debris produced during stone (lithic) tool manufacture.
Lithic scatter A distribution of cultural items that consists primarily of lithic (stone) material.