Earth Science 12th Edition Vocabulary Chapter 19

By Megan Andrews (GLY 1001 Student North Campus Fall 2006)


air-mass - a large body of air that is characterized by a sameness of temperature humidity.


air-mass weather - the conditions experienced in an area as an air mass passes over it. Because these are large and fairly homogeneous, This type of weather will be fairly constant and may last for several days.


Artic (A) air mass A bitterly cold air mass that forms over the frozen Artic Ocean


cold front - a front along which a cold air mass thrusts beneath a warmer air mass.


Continental (c) air mass - an air mass which forms over land; it is normally relatively dry.


Doppler Radar - in addition to the tasks performed by conventional radar, this new generation of weather radar can detect motion directly and hence greatly improve tornado and severe storm warnings.


eye - a zone of scattered clouds and calm averaging about 120 kilometers in diameter at the center of a hurricane.


eye wall - the doughnut-shaped area of intense cumulonimbus development and very strong winds that surrounds the eye of a hurricane.


front - the boundary between two adjoining air masses having contrasting characteristics.


hurricane - a tropical cyclonic storm having winds in excess of 119 kilometers(74 miles) per hour.


lake-effect snow - snow showers associated with a continental Polar cP air mass to which moisture and heat are added from below as the air mass traverses a large and relatively warm lake, rendering the air mass humid and unstable.


Maritime (m) air mass - an air mass that originates over the ocean. These air masses are relatively humid.


middle-latitude or mid latitude cyclone - large center of low pressure with an associated cold front and often a warm front. Frequently accompanied by abundant precipitation.


occluded front - a front formed when a cloud front overtakes a warm front. it marks the beginning of the end of a middle latitude cyclone.


occlusion - the overtaking of one front by another.


overrunning - warm air gliding up a retreating air mass.


Polar (P) air mass - a cold air mass that forms in a high latitude source region.


source region - the area where an air mass acquires its characteristic properties of temperature and moisture.


stationary front - a situation in which the surface position of a front doest not move; the flow on either side of such a boundary is nearly parallel to the position of the front.


storm surge - the abnormal rise of the sea along a shore as a result of strong winds.


thunderstorm - a storm produced by a cumulonimbus cloud and always accompanied by lightning and thunder. It is of relatively short duration and usually accompanied by strong wind gusts, heavy rain, and sometimes hail.


tornado - a small very intense cyclonic storm with exceedingly high winds, most often produced along cold fronts in conjunction with severe thunderstorms.


tornado warning - a warning issued when a tornado has actually been sighted in an area or is indicated by radar.


tornado watch - a warning issued for areas of about 65,000 sq kilometers indicating that conditions are such that tornadoes may develop; it is intended to alert people to the possibility of tornadoes.


tropical depression - By international agreement, a tropical cyclone with maximum winds that do not exceed 61 kilometers (38 miles) per hour.


tropical (T) air mass - a warm air mass that forms in a low latitude source region.


tropical storm - by international agreement a tropical cyclone with maximum winds between 61 and 119 kilometers per hour.


warm front - a front along which a warm air mass overrides a retreating mass of cooler air.