Weather terms starting with N

130 terms

N North
Nacreous Clouds Clouds of unknown composition that have a soft, pearly luster and that form at altitudes about 25 to 30 km above the Earth's surface.
NADIR The point on any given observer's celestial sphere diametrically opposite of one's zenith.
NAM The operational North American Meso (NAM, formerly Eta) is run four times per day (00,06,12,18Z), all cycles run to 84-h.
Nanotesla (nT) A unit of magnetism equal to 10-9 tesla, equivalent to a gamma (10-5 gauss).
NAO North Atlantic Oscillation - the NAO is a large-scale fluctuation in atmospheric pressure between the subtropical high pressure system located near the…
NAO Index This index measures the anomalies in sea level pressure between the Icelandic low pressure system and the Azores high pressure system in the North…
Naphtha A generic term applied to a petroleum fraction with an approximate boiling range between 122 and 400 degrees Fahrenheit.
National Ambient Air Quality Standards In the United States, national standards for the ambient concentrations in air of different air pollutants designed to protect human health and welfare.
National Climatic Data Center The agency that archives climatic data from the National Oceanic and Atmospheric Administration, as well as other climatological organizations.
National Digital Forecast Database (NDFD)- The National Weather Service's NDFD provides access to gridded forecasts of sensible weather elements (e.g.
National Fire Danger Rating System A uniform fire danger rating system used in the United States that focuses on the environmental factors that impact the moisture content of fuels.
National Flood Summary This NWS daily product (abbreviated FLN) contains nationwide information on current flood conditions.
National Geodetic Vertical Datum (NGVD) of 1929 [NGVD 1929] A fixed reference adopted as a standard geodetic datum for elevations determined by leveling.
National Hurricane Center One of three branches of the Tropical Prediction Center (TPC). This center maintains a continuous watch on tropical cyclones over the Atlantic, Caribbean…
National Hurricane Operations Plan (NHOP) - The NHOP is issued annually by the Federal Coordinator for Meteorological Services and Supporting Research.
National Severe Storms Laboratory This is one of NOAA's internationally known Environmental Research Laboratories, leading the way in investigations of all aspects of severe weather.
National Weather and Crop Summary A product of the National Agricultural Statistics Service, Agricultural Statistics Board, and U.S. Department of Agriculture.
Natural Control A stream gaging control which is natural to the stream channel, in contrast to an artificial control structure by man.
Natural gas A hydrocarbon gas obtained from underground sources, often in association with petroleum and coal deposits.
Natural gas liquids (NGLs) Those hydrocarbons in natural gas that are separated as liquids from the gas. Includes natural gas plant liquids and lease condensate.
Nautical Dawn The time at which the sun is 12 degrees below the horizon in the morning. Nautical dawn is defined as that time at which there is just enough sunlight for…
Nautical Dusk The time at which the sun is 12 degrees below the horizon in the evening. At this time, objects are no longer distinguishable.
Nautical Mile A unit of distance used in marine navigation and marine forecasts. It is equal to 1.15 statue miles or 1852 meters.
Nautical Twilight The time after civil twilight, when the brighter stars used for celestial navigation have appeared and the horizon may still be seen.
Navigation Methods Three basic methods of providing and managing inland waterways - 1) Run-of-the-River: no provision of upstream storage; 2) Slack-Water: locks and dams…
NAVTEX An international automated medium frequency (518 kHz) direct-printing service for delivery of navigational and meteorological warnings and forecasts, as…
NAVTEX Forecast (NAV) - A National Weather Service marine forecast combining various Coastal Waters and Offshore forecasts, optimized to accommodate transmission via…
NBND Northbound
NC 1. No change 2. North Carolina
NCAR National Center for Atmospheric Research
NCCF NOAA Central Computer Facility
NCDC National Climatic Data Center
NCEP National Centers for Environmental Prediction. A part of the National Weather Service which provides nationwide computerized and manual guidance to…
NDBC National Data Buoy Center
NDFD (National Digital Forecast Database) - The National Weather Service's NDFD provides access to gridded forecasts of sensible weather elements (e.g.
NE Northeast
Neap Tide A minimum tide occurring at the first and third quarters of the moon.
Near Real Time When referred to in textual references, the ARM conception of "near-real time" is "with a few hours delay."
near-surface soil heat flux A quantity measured near the surface of the soil, according to the formula B = λ(dT/dz), where λ is the conductivity of the soil that the heat or…
near-surface soil moisture flux A quantity measured near the surface of the soil, according to the formula B = λ(dq/dz), where λ is the conductivity of the soil that the heat or…
Nearshore Forecast (NSH) - National Weather Service seasonal marine forecasts for an areas of the Great Lakes extending from a line approximating mean low water datum along…
NEC Necessary
NEG Negative
negative feedback the process by which an initial change brings about an additional change in the opposite direction.
Negative Vorticity Advection (Abbrev. NVA) - the advection of lower values of vorticity into an area.
Negative-tilt Trough An upper level system which is tilted to the west with increasing latitude (i.e., with an axis from southeast to northwest).
NELY Northeasterly
NERN Northeastern
NESDIS National Environmental Satellite, Data, and Information Service. NESDIS collects, processes, stores, analyzes, and disseminates various types of…
Net All-Wave Radiation The net or resultant value of the upward and downward longwave and shortwave radiative fluxes through a plane at the earth-atmosphere interface; a…
net radiation The difference between upwelling and downwelling, covering longwave and shortwave radiation.
Net Rainfall The portion of rainfall which reaches a stream channel or the concentration point as direct surface flow.
Net terrestrial radiation Net terrestrial radiation Difference between the downward and upward terrestrial radiation fluxes; net flux of terrestrial radiation.
Neutral Line The line that separates longitudinal magnetic fields of opposite polarity.
Neutral Stability An atmospheric condition that exists in unsaturated air when the environmental lapse rate equals the dry adiabatic rate, or in saturated air when the…
NEWD Northeastward
NEXRAD NEXt Generation RADar. A NWS network of about 140 Doppler radars operating nationwide.
NGM The Nested Grid Model, a 48-hour numerical model of the atmosphere run twice daily by NCEP.
NGT Night
NHC National Hurricane Center - one of three branches of the Tropical Prediction Center (TPC).
NHOP (National Hurricane Operations Plan) - The NHOP is issued annually by the Federal Coordinator for Meteorological Services and Supporting Research.
Nieve Penitente A spike or pillar of compacted snow, firn or glacier ice, caused by differential melting and evaporation.
Night The period of the day between dusk and dawn.
NIL Nothing; of no account.
Nimbostratus (abbrev. NS)- A cloud of the class characterized by a formless layer that is almost uniformly dark gray; a rain cloud of the layer type, of low altitude…
nitrogen A colorless, tasteless element that comprises four-fifths of the atmosphere by volume, denoted by N2.
Nitrogen cycle Cyclic movement of nitrogen in different chemical forms from the environment, to organisms, and then back to the environment.
Nitrogen fixation The conversion of atmospheric nitrogen to biologically usable nitrates.
Nitrogen Oxides (NOx) The products of all combustion processes formed by the combination of nitrogen and oxygen.
Nitrous Oxide (N2O) A powerful greenhouse gas with a global warming potential of 296 times that of carbon dioxide (CO2).
Nitrous Oxide (N<sub>2</sub>O) A powerful greenhouse gas with a global warming potential most recently evaluated at 310.
NLY Northerly
NM Nautical Miles
NMBR Number
NMC National Meteorological Center
NML Normal
NMRS Numerous
NOAA National Oceanic and Atmospheric Administration
NOAA Weather Radio "The voice of the National Weather Service" - NOAA Weather Radio broadcasts National Weather Service warnings, watches, forecasts and other hazard…
NOAA Weather Wire Mass dissemination via satellite of National Weather Service products to the media and public.
Noctilucent Clouds Wavy, thin, bluish-white clouds that are best seen at twilight in polar latitudes. They form at altitudes about 80 to 90 km above the Earth's surface.
Nocturnal Related to nighttime; occurring at night.
Nocturnal Inversion Used interchangably with Radiational Inversion; a temperature inversion that develops during the night as a result of radiational cooling of the surface.
Nocturnal Jet This wind speed maximum occurs just above the nocturnal inversion at night. It is typically found in the south central United States during the late…
Nocturnal Thunderstorms Thunderstorms which develop after sunset. They are often associated with the strengthening of the low level jet and are most common over the Plains states.
NOGAPS Navy Operational Global Atmospheric Prediction System; a 144-hour numerical model of the atmosphere run by the U.S. Navy twice daily.
NOHRSC In hydrologic terms, the National Operational Hydrologic Remote Sensing Center.
non-linear a system that is not describable as the sum of its parts and, as a result, is difficult to predict.
Non-Methane Volatile Organic Compounds (NMVOCs) Organic compounds, other than methane, that participate in atmospheric photochemical reactions.
Non-point source Large land area such as crop fields and urban areas that discharge pollutant into surface and underground water over a large area. See point source.
Non-Uniform Sky Condition A localized sky condition which varies from that reported in the body of the report.
Non-Uniform Visibility A localized visibility which varies from that reported in the body of the report.
Nonattainment Area The EPA's designation for an air quality control region (or portion thereof) in which ambient air concentrations of one or more criteria pollutants exceed…
Nonbiodegradable Substance that cannot be broken down in the environment by natural processess. See biodegradable.
Nonlinearities Occur when changes in one variable cause a more than proportionate impact on another variable.
Nor\'easter A strong low pressure system that affects the Mid Atlantic and New England States. It can form over land or over the coastal waters.
Normal The long-term average value of a meteorological paramater (i.e., temperature, humidity, etc.) for a certain area.
Normal Water Surface Elevation In hydrologic terms, the lowest crest level of overflow on a reservoir with a fixed overflow level (spillway crest elevation).
Normal Year A year during which the precipitation or stream flow approximates the average for a long period of record.