Subj : Weather Terms (F) Part 1 To : All From : Daryl Stout Date : Wed Sep 07 2016 03:29 am F 1) Fahrenheit- The standard scale used to measure temperature in the United States. On this scale, the freezing point of water is 32øF and the boiling point is 212øF. To convert a Celsius temperature to Fahrenheit, multiply it by 9/5 and then add 32: øF = (øC * 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 ¬ mile or less. F Corona 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. F Region 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. F Scale Abbreviation for Fujita Scale, a system of rating the intensity of tornadoes; for detailed information, see the definition for that term. FA Forecast Area FAA Federal Aviation Administration Face In hydrologic terms, the external surface of a structure, such as the surface of a dam. Facula In solar-terrestrial terms, a bright region of the photosphere seen in white light, seldom visible except near the solar limb. Fahrenheit (abbrev. F) The standard scale used to measure temperature in the United States. On this scale, the freezing point of water is 32øF and the boiling point is 212øF. To convert a Celsius temperature to Fahrenheit, multiply it by 9/5 and then add 32: øF = (øC * 9/5) + 32 Fair 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. Fall 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. Fall Line A skiing term, indicating the line of steepest descent of a slope. Fall Wind A strong, cold, downslope wind. Fallstreak 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. FAN AVN MOS Guidance (older version) Fanning 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. FASTST Fastest Fathom Unit of water depth equal to 6 feet. FAWS Flight Advisory Weather Service FBO (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. FCST Forecast Federal Snow Sampler In hydrologic terms, a snow sampler consisting of five or more sections of sampling tubes, one which has a steel cutter on the end. The combined snowpack measuring depth is 150 inches. This instrument was formerly the Mount Rose Type Snow Sampling Set. Feeder Bands Lines or bands of low-level clouds that move (feed) into the updraft region of a thunderstorm, usually from the east through south (i.e., parallel to the inflow). Same as inflow bands. This term also is used in tropical meteorology to describe spiral-shaped bands of convection surrounding, and moving toward, the center of a tropical cyclone. FEMA Federal Emergency Management Agency. An agency of the federal government having responsibilities in hazard mitigation; FEMA also administers the National Flood Insurance Program. Ferrel Cell In the general circulation of the atmosphere, the name given to the middle latitude cell marked by sinking motion near 30 degrees and rising motion near 60 degrees latitude. Fetch 1. The area in which ocean waves are generated by the wind. Also refers to the length of the fetch area, measured in the direction of the wind. 2. In hydrologic terms, The effective distance which waves have traversed in open water, from their point of origin to the point where they break. 3. The distance of the water or the homogenous type surface over which the wind blows without appreciable change in direction. Few A National Weather Service convective precipitation descriptor for a 10 percent chance of measurable precipitation (0.01 inch). Few is used interchangeably with isolated. Few Clouds An official sky cover classification for aviation weather observations, descriptive of a sky cover of 1/8 to 2/8. This is applied only when obscuring phenomenon aloft are present--that is, not when obscuring phenomenon are surface-based, such as fog. FFG Flash Flood Guidance FG (Also abbrev. F) - Fog - water droplets suspended in the air at the Earth's surface. Fog is often hazardous when the visibility is reduced to ¬ mile or less. Fibril In solar-terrestrial terms, a linear pattern in the H-alpha chromosphere of the sun, as seen through an H-alpha filter, occurring near strong sunspots and plage or in filament channels. Field (Moisture) Capacity The amount of water held in soil against the pull of gravity. Field Moisture Deficiency The quantity of water, which would be required to restore the soil moisture to field moisture capacity. Filament A mass of gas suspended over the photosphere by magnetic fields and seen as dark lines threaded over the solar disk. A filament on the limb of the sun seen in emission against the dark sky is called a prominence. Filament Channel A broad pattern of fibrils in the chromosphere, marking where a filament may soon form or where a filament recently disappeared. Fill Dam In hydrologic terms, any dam constructed of excavated natural materials or of industrial wastes. Filling The opposite of deepening. A general increase in the central pressure of a low pressure system. Fire Wind A thermally driven wind blowing radially inward toward a fire, produced by horizontal temperature differences between the heated air above the fire and the surrounding cooler free atmosphere. Firebrand Any source of heat, natural or man made, capable of igniting wildland fuels; flaming or glowing fuel particles that can be carried naturally by wind, convection currents, or gravity into unburned fuels. Firn (Snow) In hydrologic terms, old snow on top of glaciers, granular and compact and not yet converted into ice. It is a transitional stage between snow and ice. Also called Neve. Firn Line In hydrologic terms, the highest level to which the fresh snow on a glacier's surface retreats during the melting season. The line separating the accumulation area from the ablation area. Posted by VPost v1.7.081019 --- Virtual Advanced Ver 2 for DOS * Origin: The Thunderbolt BBS (801:1/7) þ Synchronet þ The Curmudeon's Place .