Weather Glossary - F
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F scaleSee Fujita Scale. |
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Fahrenheit scaleThe temperature scale where 32°F is the freezing point of water and 212°F is the boiling point (at sea level). |
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Fahrenheit temperature scaleThermodynamic scale of temperature. Temperature in degrees Fahrenheit can be obtained from value in degrees Celsius by the following formula: F=(9C/5)+32 |
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Feeder bandsLines or bands of low-level clouds that move (feed) into the updraft region of a thunderstorm, usually from the north through east (i.e., parallel to the inflow). Same as inflow bands. This term also is used in tropical meteorology to describe the spiral-shaped bands of convection surrounding and moving toward the centre of a tropical cyclone. |
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Feels LikeThe 'Feels Like' Index displayed in the Observations pages on Weatherzone is a combination of the heat index and wind chill factor. |
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FetchDistance, measured in the upward wind direction. Fetch is important in determining swell size. The longer the fetch the higher the swell. |
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FewDescribes cloud cover when between 1/8th and 2/8th of the sky is obscured by cloud. |
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FillingDescribes an increase in the central pressure of a low pressure system. |
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Flang[Slang] FLash bANG, a very close lightning strike followed immediately by thunder. |
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Flanking lineA line of cumulus or towering cumulus clouds connected to and extending outward from the most active part of a thunderstorm, normally on the northwest side. The line normally has a stair-step appearance, with the tallest clouds closest to the main storm and generally coincides with the pseudo-cold front. See HP storm and supercell. |
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Flash floodHeavy rainfall and localised flooding of short duration with a relatively high peak discharge. Often caused by severe thunderstorms or intense rainfall events such as an East Coast Low. For severe thunderstorms, a flash flood event is considered to be a 1 in 10 year rainfall event. |
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Flash floodingShort duration localised flooding caused by heavy rainfall with a relatively high peak discharge. Often caused by severe thunderstorms or intense rainfall events such as an East Coast Low. For severe thunderstorms, a flash flood event is considered to be a 1 in 10 year rainfall event. |
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FloodA flood occurs when water inundates (covers) land which is normally dry. |
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Foehn effectThe warming effect of air flowing down the leeward side of a mountain range. The heating and drying of the air is due to adiabatic compression of the air as it flows down the slope. |
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FogA dense mass of small water droplets suspended in the air near the ground. Visibility is reduced to less than 1 kilometre. See also Radiation fog, Advection Fog, Upslope fog and Mist. |
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Forced convectionMotion forced by mechanical forces such as deflection or friction. A cold front will cause forced convection as warmer is forced vertically above advancing cooler air. |
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Forward flank downdraftThe main region of downdraft in the forward, or leading, part of a supercell, where most of the heavy precipitation is. Compare with rear flank downdraft. See pseudo-warm front and supercell. |
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FractusLatin - to break or fracture |
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Free convectionMotion caused only by density differences in a fluid. See also Level of Free Convection |
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FreezeThe phase change of a liquid to solid. |
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Freezing rainRain that becomes supercooled and freezes on impact with the ground or with objects on the earth's surface. Freezing rain can cause great damage, due to the weight of ice accumulating on structures in extreme events. Freezing rain is not a common event in Australia. |
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FrontA boundary or transition zone between two air masses of different density, and thus (usually) of different temperature. A moving front is named according to the advancing air mass, e.g., cold front if colder air is advancing. Fronts can be a region of localised lifting, leading to rainfall or thunderstorms. |
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FrontogenesisThe process where a front is either created or intensifying. Occurs when two adjacent air masses exhibiting different characteristics are brought together by prevailing winds. |
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FrostDeposits of white ice crystals or frozen dew drops on objects on or near the ground. Formed when the surface temperature falls below freezing (0°). |
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Fujita Scale(or F Scale) A scale of wind damage intensity in which wind speeds are inferred from an analysis of wind damage:
All tornadoes, and most other severe local windstorms, are assigned a single number from this scale according to the most intense damage caused by the storm. |
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Funnel cloudA condensation funnel extending from the base of a towering cumulus or Cb, associated with a rotating column of air that is not in contact with the ground (and hence different from a tornado). A condensation funnel is a tornado, not a funnel cloud, if either
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FusionThe phase from a solid to a liquid. |
Weather News
Soggy week ahead for parts of QLD
13:41 EST
A moisture laden trough will linger across northern and eastern Queensland through the week to come, resulting in large rainfall accumulations.
Super Typhoon Surigae threatening the Philippines with dangerous surf, rain and winds
13:08 EST
Super Typhoon Surigae, as it was named by the JTWC, has strengthened and is looming over the Philippines.