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Weather Resources - Glossary

Wondering what “graupel” is? Or how about “virga”? You have come to the right place. This section contains the definitions of several hundred weather related terms.

Please contact us if you have a suggestion for additional terms.

We have also developed a special glossary section with winter weather terms only.

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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.

Flanking Line - A line of cumulus or towering cumulus clouds connected to and extending outward from the most active part of a supercell, normally on the southwest 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.

Forward Flank Downdraft - The main region of downdraft in the forward, or leading, part of a supercell, where most of the heavy precipitation is. Compare with rearrear flank downdraft.

Front - A 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.

Fractus - Ragged, detached cloud fragments; same as scud.

Fujita Scale (or F Scale) - Replaced by the Enhanced Fujita Scale (or EF Scale) in 2007. See Enhanced Fujita Scale.

Funnel Cloud - A tornado that hasn't reached the ground. It appears as a rotating, cone like cloud that extends out of the base of a thunderstorm. A 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 a) it is in contact with the ground or b) a debris cloud or dust whirl is visible beneath it.

Portions of the 9NEWS Weather Glossary were taken from the second edition of the Glossary of Meteorology published by the American Meteorological Society (AMS). © 2009 American Meteorological Society