1) Fahrenheit- The standard scale used to measure temperature in the United States. On this scale, the freezing point of water is 32°F and the boiling point is 212°F. To convert a Celsius temperature to Fahrenheit, multiply it by 9/5 and then add 32: °F = (°C * 9/5) + 32
or
2) Fog- Water droplets suspended in the air at the Earth's surface. Fog is often hazardous when the visibility is reduced to ¼ mile or less.
- Browse Related Terms: Azimuth, Celsius, Declination, F, Fahrenheit, Kelvin Temperature Scale, STJ, Subtropical Jet, Tropics
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In solar-terrestrial terms, of the white-light corona (that is, the corona seen by the eye at a total solar eclipse), that portion which is caused by sunlight scattered or reflected by solid particles (dust) in inter-planetary space.
- Browse Related Terms: Active Surge Region (ASR), Bright Surge on the Disk (BSD), Bright Surge on the Limb (BSL), Chromosphere, Coronal Hole, Coronal Transients, Dark Surge on Disk (DSD), F Corona, Facula, Granulation, K Corona, Prominence
In solar-terrestrial terms, the upper layer of the ionosphere, approximately 120 to 1500 km in altitude. The F region is subdivided into the F1 and F2 regions. The F2 region is the most dense and peaks at altitudes between 200 and 600 km. The F1 region is a smaller peak in electron density, which forms at lower altitudes in the daytime.
- Browse Related Terms: D Region, E REGION, F Region, fMin, foEs, foF2, Sporadic E
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Abbreviation for Fujita Scale, a system of rating the intensity of tornadoes; for detailed information, see the definition for that term.
- Browse Related Terms: Corner Effects, F Scale, FPS, Rope, Rope Stage, SSHS, Suction Vortex, Wedge Tornado
Forecast Area
- Browse Related Terms: 1-2-3 Rule, AGFS, Complex Gale/Storm, CWFA, Developing Gale/Storm, FA, FCST, FOUS, Grids, High Seas Forecast, Marine Zone, NSSFC, OFSHR, PROGGED, Radar Meteorology, RAFC, RAFS, Red Flag Warning, TAF, Valid Time, ZFP
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In hydrologic terms, the external surface of a structure, such as the surface of a dam.
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In solar-terrestrial terms, a bright region of the photosphere seen in white light, seldom visible except near the solar limb.
- Browse Related Terms: Active Surge Region (ASR), Bright Surge on the Disk (BSD), Bright Surge on the Limb (BSL), Chromosphere, Coronal Hole, Coronal Transients, Dark Surge on Disk (DSD), F Corona, Facula, Granulation, K Corona, Prominence
(abbrev. F) The standard scale used to measure temperature in the United States. On this scale, the freezing point of water is 32°F and the boiling point is 212°F. To convert a Celsius temperature to Fahrenheit, multiply it by 9/5 and then add 32:
°F = (°C * 9/5) + 32
- Browse Related Terms: Azimuth, Celsius, Declination, F, Fahrenheit, Kelvin Temperature Scale, STJ, Subtropical Jet, Tropics
It is usually used at night to describe less than 3/8 opaque clouds, no precipitation, no extremes of visibility, temperature or winds. It describes generally pleasant weather conditions.
- Browse Related Terms: AURORA, Broken Level, Cloudy, Convective Overdevelopment, Fair, Jet Stream Cirrus, Mostly Clear, Mostly Cloudy, Mostly Sunny, Okta, Opaque, Partly Cloudy, Partly Sunny, RPD, Shallow Fog, Shower, Sky Condition, Sunny
the season of the year which is the transition period from summer to winter occurring as the sun approaches the winter solstice. In the Northern Hemisphere, fall customarily includes the months of September, October and November.
- Browse Related Terms: Autumn, Autumnal Equinox, Fall, Hurricane Season, Nautical Twilight, OHD, Solar Noon, Solstice, Summer, Summer Solstice, Winter, Winter Solstice
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A skiing term, indicating the line of steepest descent of a slope.
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A strong, cold, downslope wind.
- Browse Related Terms: Aeroallergens, Blowing Dust or Sand, Dust Storm, Fall Wind, Firebrand, Mesoscale High Winds, Plume-dominated Fire, Ribbon Lightning, Sandstorm, Santa Ana Wind, Spotting
Same as Virga; streaks or wisps of precipitation falling from a cloud but evaporating before reaching the ground. In certain cases, shafts of virga may precede a microburst.
- Browse Related Terms: Drizzle, Fallstreak, FLG, Hail, Rain Foot, Snow Grains, Snow Pellets, Virga, VMD, Wet Microburst
AVN MOS Guidance (older version)
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A pattern of plume dispersion in a stable atmosphere, in which the plume fans out in the horizontal and meanders about at a fixed height.
- Browse Related Terms: aerosol, Coning, Entrainment Zone, Fanning, Fumigation, Lofting, Looping, Mixing Heights, STBL
Fastest
- Browse Related Terms: ABT, ABV, ACRS, AFT, AFTR, AGN, ALG, ALTHO, AMD, AOA, AOB, ARND, AVBL, BCM, BCMNG, BFR, BGN, BHND, BLO, BLV, BRF, BTR, BTWN, BYD, CFC, CHGS, CLR, DMSH, DURG, EBND, EFCT, ELSW, ENDG, ERLY, EXCLD, FASTST, FM, FTHR, GEN, GNRL, GRT, GRTST, GTR, HND, HV, HWVR, IMPT, INDC, LN, LRG, LTL, LTR, LTST, MDNGT, METRO, MISC, MISG, MNLY, MR, MSTLY, NBND, NEC, NIL, NLY, NMBR, NR, NWLY, NWRD, NWRN, NXT, OTR, OTRW, OVR, PCT, PRBLY, PSBL, PSBLY, QG, RIOGD, RTRD, RW, SBND, SEWD, SGFNT, SPCLY, SS-, Sun Dog, SVRL, SWWD, SXN, TDA, THRFTR, THRU, THRUT, TIL, TWD, WBND, WL, XCITED, YDA
Unit of water depth equal to 6 feet.
- Browse Related Terms: Acre-foot, Adirondack Type Snow Sampling Set, CFS, Cfs-Day, Cubic Feet per Second, Evaporation rate, Fathom, Federal Snow Sampler, FT, Infiltration Rate, Second-Day Feet
Flight Advisory Weather Service
- Browse Related Terms: Air Stagnation Advisory, Brisk Wind Advisory, Daily Climatological Report, Excessive Heat Watch, FAWS, Hazardous Weather Outlook, Heavy Surf Advisory, Monthly Climatological Report, Record Event Report, Severe Local Storm Watch, Significant Weather Outlook, Special Avalanche Warning
(Great Lakes Freeze-Up/Break-Up Outlook) - A National Weather Service product to keep mariners informed of the projected freeze-up date or break-up date of ice on the Great Lakes.
- Browse Related Terms: Air pollutant, APST, FBO, FTPMAIL, Great Lakes Faxback, Great Lakes Freeze-Up/Break-Up Outlook, NESDIS, NOAA Weather Wire, Offshore Waters Forecast, Recreation Report, Severe Weather Statement, Short Term Forecast, SRF, St Lawrence Freeze-Up Outlook, State Forecast Product, Surf Zone Forecast, Wind Radii