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Fujita Scale- System developed by Dr. Theodore Fujita to classify tornadoes based on
wind damage. Scale is from F0 for weakest to F5 for strongest tornadoes.
Gale- Sustained wind speeds from 34 to 47 knots (39 to 54 mph).
High- An area of high pressure, usually accompanied by anticyclonic and outward wind
flow. Also known as an anticyclone.
Humidity- The amount of water vapor in the atmosphere.
Hurricane- A severe tropical cyclone with sustained winds over 74 mph (64
knots). Normally applied to such storms in the Atlantic Basin and the Pacific Ocean
east of the International Date Line.
Isobar- A line of equal barometric pressure on a weather map.
Knot- A measure of speed. It is one nautical mile per hour (1.15 mph). A nautical mile
is one minute of one degree of latitude.
Lightning- Any form of visible electrical discharges produced by thunderstorms.
Low- An area of low pressure, usually accompanied by cyclonic and inward wind flow.
Also known as a cyclone.
Millibar- A metric unit of atmospheric pressure. 1 mb = 100 Pa (Pascal). Normal
surface pressure is approximately 1013 millibars.
NEXRAD: NEXt Generation RADar. A NWS network of about 140 Doppler radars
operating nationwide.
NOAA- National Oceanic and Atmospheric Administration. A branch of the U.S.
Department of Commerce, NOAA is the parent organization of the National Weather
Service.
Occluded Front- A complex frontal system that occurs when a cold front overtakes a
warm front. Also known as an occlusion.
Pressure- The force exerted by the interaction of the atmosphere and gravity. Also
known as atmospheric pressure.
Relative Humidity- The amount of water vapor in the air, compared to the amount the
air could hold if it was totally saturated. Expressed as a percentage.
Squall- A strong wind characterized by a sudden onset in which the wind speed
increases at least 16 knots and is sustained at 22 knots or more for at least one minute.