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| an immense body of air that is characterized by a similarity of temperature and moisture at any given altitude |
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| since it may take several days for an air mass to move across an area, the region under its influence will probably experience fairly constant weather |
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| the area where an air mass acquires its characteristic properties of temperature and moisture |
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| polar (P) and arctic (A) air masses |
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| originate in high latitudes toward Earth's poles; cold |
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| those that form in low latitudes; warm |
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| continental (c) air masses |
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| form over land; likely to be dry |
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| originate over water; likely to be humid |
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| localized storms that deposit snow across a lake when the surface weather map indicates no apparent cause for a snowstorm to occur |
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| boundaries that separate air masses of different densities |
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| generally applied to warm air gliding up along a cold air mass |
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| when the surface (ground) position of a front moves so that warm air occupies territory formerly covered by cooler air |
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| when cold air actively advances into a region occupied by warmer air |
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| when the surface position of the front does not move |
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| an active cold front overtakes a warm front; as the cold air forces the warm front upward, a new front emerges between the cold air and the air over which the warm front is gliding |
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primary weather producers in between Florida and Alaska shown by an L (low-pressure center) on weather maps
also known as midlatitude cyclones |
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| the position of a cold front advances faster than the warm front and begins to close the warm front which forms an occluded front; creates intense storms |
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| a storm that generates lightning and thunder |
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| local storms of short duration that must be ranked high among nature's most destructive forces |
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| Enhanced Fujita (EF) intensity scale |
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| a commonly used guide to measure tornado intensity; determined by assessing the worst damage produced by the storm |
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| alert the public to the possibility of tornadoes over a specified area for a particular time interval |
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| issued by local offices of the National Weather Service when a tornado has actually been sighted in an area or is indicated by weather radar |
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| radar that not only performs the same tasks as conventional radar but also has the ability to detect motion directly |
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| whirling tropical cyclones that on occasion have wind speeds attaining 300 km per hour; they are the greatest storms on Earth |
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| doughnut-shaped wall of intense convective activity surrounding the center of the storm |
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| very center of the hurricane that offers a brief but deceptive break from the extreme weather in the enormous curving wall clouds that surround it |
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| many tropical storms begins as disorganized arrays of clouds and thunderstorms that develop weak pressure gradients but exhibit little or no rotation |
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| when a cyclone's strongest winds do not exceed 61 km per hour |
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| when winds are between 61 and 119 km per hour; during this phase the storm is named |
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| established to rank the relative intensities of hurricanes |
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| a dome of water 65-80 km wide that sweeps across the coast near the point where the eye makes landfall |
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