Weather terms starting with L

131 terms

La Niña La Niña, a phase of ENSO, is a periodic cooling of surface ocean waters in the eastern tropical Pacific along with a shift in convection in the western…
Lag Refers to slow game response times. The cause can be graphical based (weak graphics card), internet based (ping), system based (lack of memory, virtual…
Lake Breeze A thermally produced wind blowing during the day from the surface of a large lake to the shore, caused by the difference in the rates of heating of the…
Lake Effect Snow Snow showers that are created when cold, dry air passes over a large warmer lake, such as one of the Great Lakes, and picks up moisture and heat.
Lake Effect Snow Advisory This product is issued by the National Weather Service when pure lake effect snow (this is where the snow is a direct result of lake effect snow and not…
Lake Effect Snow Squall A local, intense, narrow band of moderate to heavy snow squall that can extend long distances inland. It may persist for many hours.
Lake Effect Snow Warning This product is issued by the National Weather Service when pure lake effect snow (this is where the snow is a direct result of lake effect snow and not…
Lake Effect Storm A fall or winter storm that produces heavy but localized precipitation as a result of temperature differences between the air over snow-covered ground and…
Lakeshore Flood Advisory See Coastal/Lakeshore Flood Advisory.
Lakeshore Flood Watch See: COASTAL/LAKESHORE FLOOD WATCH
Lakeshore Flooding See COASTAL/LAKESHORE FLOODING
LALs (L)ightning (A)ctivity (L)evels. LAL 1 - No thunderstorms. LAL 2 - Few building cumulus with isolated thunderstorms.
Laminar Smooth, non-turbulent. Often used to describe cloud formations which appear to be shaped by a smooth flow of air traveling in parallel layers or sheets.
Laminar Flow Flow in which the head loss is proportional to the first power of the velocity.
Land Breeze A coastal breeze at night blowing from land to sea, caused by the difference in the rates of cooling of their respective surfaces.
Land sky Land sky The relatively dark appearance of the underside of a cloud layer when it is over land that is not snow covered.
Landfall The intersection of the surface center of a tropical cyclone with a coastline. Because the strongest winds in a tropical cyclone are not located precisely…
Landfill An open area where trash is buried. Facility in which solid waste from municipal and/or industrial sources is disposed; sanitary landfills are those that…
Landspout [Slang], a tornado that does not arise from organized storm-scale rotation and therefore is not associated with a wall cloud (visually) or a mesocyclone…
Lapse Rate The rate of change of an atmospheric variable, usually temperature, with height.
Large Scale (Synoptic Scale) Size scale referring generally to weather systems with horizontal dimensions of several hundred miles or more.
Large-scale atmospheric processes Large-scale atmospheric processes (circulation) Atmospheric processes with a representative scale (large-scale) of 10 000 km.
Last Update The time and date in which the forecast was issued or updated. The forecast may be updated at any time as weather conditions warrant.
LAT Latitude- The location north or south in reference to the equator, which is designated at zero (0) degrees.
Latent Heat The change in heat content that occurs with a change in phase and without change in temperature.
Latent Heat Flux The flux of heat from the earth's surface to the atmosphere that is associated with evaporation or condensation of water vapor at the surface; a component…
Latitude (abbrev. LAT) The location north or south in reference to the equator, which is designated at zero (0) degrees.
Laurentide ice sheet the ice sheet that grew over a large part of North America during the last glacial period.
LAWEB (Great Lakes Weather Broadcast) - A National Weather Service product containing an observation summary prepared to provide Great Lakes mariners with a…
Layer Composite Reflectivity Average This WSR-88D radar product displays the average reflectivities for a layer. Data is taken from all elevation angles contained in a given layer for each…
Layer Composite Reflectivity Maximum This WSR-88D radar product displays the maximum reflectivities for a layer. Data is taken from all elevation angles contained in a given layer for each…
Layered Haze Haze produced when air pollution from multiple line, area or point sources is transported long distances to form distinguishable layers of discoloration…
LCD (Local Climatological Data) This National Climatic Data Center (NCDC) publication is produced monthly and annually for some 270 United States cities and it's territories.
LCL 1. Abbreviation for "local" or "locally" 2. Lifting Condensation Level - the level at which a parcel of moist air becomes saturated when it is lifted dry…
LDS Lightning Detection System
LDT Local Daylight Time.
Leader The streamer which initiates the first phase of each stroke of a lightning discharge.
Leader Spot In solar-terrestrial terms, in a magnetically bipolar or multipolar sunspot group, the western part precedes and the main spot in that part is called the…
Lee The side or part that is sheltered or turned away from the wind, such as with a mountain.
Lee Wave The wavelike effect, characterized by severe updrafts and downdrafts, that occurs in the lee of a mountain range when rapidly flowing air is lifted up the…
Leeside Low Extratropical cyclones that form on the downwind (lee) side of a mountain chain.
Leeward The side away from the wind. Compare windward.
Left Exit Region Used interchangably with Left Front Quadrant; the area downstream from and to the left of an upper-level jet max (as would be viewed looking along the…
Left Front Quadrant Used interchangably with Left Exit Region; the area downstream from and to the left of an upper-level jet max (as would be viewed looking along the…
Left Mover A thunderstorm which moves to the left relative to the steering winds, and to other nearby thunderstorms; often the northern part of a splitting storm.
Length The distance in the direction of flow between two specific points along a river, stream, or channel.
Lentic System A nonflowing or standing body of fresh water, such as a lake or pond. Compare lotic system.
Lenticular Cloud A very smooth, round or oval, lens-shaped cloud that is often seen, singly or stacked in groups, near or in the lee of a mountain ridge.
Levee A natural or man-made barrier that helps keep rivers from overflowing their banks. See dike.
Level of Free Convection (LFC) - The level at which a parcel of saturated air becomes warmer than the surrounding air and begins to rise freely.
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
LGT Light
LGWV Long Wave
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…
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…
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
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.
Light Bridge In solar-terrestrial terms, it is observed in white light, a bright tongue or streaks penetra- ting or crossing sunspot umbrae.
Light-duty vehicles Automobiles and light trucks combined.
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).
Lignite A brownish-black coal of low rank with high inherent moisture and volatile matter content, used almost exclusively for electric power generation.
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.
Limnology Scientific study of the physical characteristics and biology of lakes, ponds, and streams.
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 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.
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 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.
Lithic Relating to stone or rock.
Lithometeor Atmospheric phenomena which affect the state of the atmosphere. They constitute dry particles that hang suspended in the atmosphere, such as dust, smoke…
Lithosphere That part of the earth which is composed predominantly of rocks (either coherent or incoherent, and including the disintegrated rock materials known as…
Litter Undecomposed plant residues on the soil surface. See decomposition.
Littoral Zone The zone or strip of land along the shoreline between the high and low water marks.
Live Capacity The total amount of storage capacity available in a reservoir for all purposes, from the dead storage level to the normal water or normal pool level…
LIVV Lifted Index Vertical Velocity
LKLY Likely- In probability of precipitation statements, the equivalent of a 60 or 70 percent chance.
LLJ Low Level Jet - A region of relatively strong winds in the lower part of the atmosphere.
LLWS Low Level Wind Shear
LMTD limited
LN Line
Loaded Gun (Sounding) [Slang], a sounding characterized by extreme instability but containing a cap, such that explosive thunderstorm development can be expected if the cap can…
Local Convective Wind In fire weather terminology, local thermally driven winds arising over a comparatively small area and influenced by local terrain.
Loess A group of windblown soils, largely comprising silt, weakly cemented by calcite.
Lofting A 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…
Long Term Retention Retention of data for 5 years to satisfy requirements for local studies and to support litigation.
Longitude The location east or west in reference to the Prime Meridian, which is designated as zero (0) degrees longitude.
longwave net radiation The difference between upwelling and downwelling broadband longwave radiation.
longwave radiance The rate at which light energy in the longwave portion of the spectrum is emitted in a particular direction per unit of projected surface area…