definitions

Definitions

Cyclone: A weather system with a low-pressure area in the center, around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Not to be confused with a tornado, which is a much smaller weather phenomenon associated with severe thunderstorms.

Density (of air): A column of air one centimeter square, measured from sea level to the top of the atmosphere, weighs about 1.4 kg (2.3 lbs). Add to that the amount of water vapor it carries and the temperature of the mass to calculate density. This figure must then be modified to account for altitude (distance above sea level).

Front: The boundary between two air masses of different densities. The density difference can be caused by differences in temperature and/or humidity.

Tornado: Localized, narrow, violent funnel of fast-spinning wind, usually generated when two air masses collide. Not to be confused with a cyclone. The oceanic equivalent of a tornado is a waterspout. (Click on the hyperlinked word tornado to find out how tornadoes work!)

Tornado Alley: The area over which tornadoes occur most often in North America is called Tornado Alley.

Tornado Chaser: a person who follows a tornado to give information.

Funnel Cloud: a funnel-shaped cloud that projects from the base of a thundercloud and that often betokens the formation of a tornado.
Fujita Scale: the scale by with tornado wind speeds are measured

Lightening: the flashing of light produced by a discharge of atmospheric electricity; also : the discharge itself

Wind Speed: determines how bad a tornado will be

Waterspout: a funnel-shaped or tubular column of rotating cloud-filled wind usually extending from the underside of a cumulus or cumulonimbus cloud down to a cloud of spray torn up by the whirling winds from the surface of an ocean or lake