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air mass

a huge body of air that has similar temp, pressure, and humidity at any given height; classified by temp and humidity


warm air masses that form in the tropics and have low air pressure


cold air masses that form at high latitudes towards poles


air masses that form over oceans


air masses that form over land and are dry

maritime tropical

form in gulf of mexico or over pacific ocean

maritime polar

form over north pacific and atlantic oceans; bring cool humid air

continental tropical

form over dry areas of southwest and northern mexico; bring hot dry weather- southern great plains

continental polar

form over central and northern canada and alaska, near arctic circle; bring clear, cold, dry air to north america (alberta clipper)


boundary between 2 air masses

cold front

a fast moving cold air mass overtakes a warm air mass; rising warm air cools, clouds forms; may bring heavy storms followed by cooler, drier air and clear skies

warm front

a warm air mass overtakes a slow moving cold air mass; warm air moves over cold air; may cause several days of precipitation followed by warm and humid air

stationary fronts

cold and warm air masses meet, but neither can move the other; water vapor in the warm air condenses into rain, snow, fog, or clouds; if stalled, may bring days of clouds and precipitation

occluded front

a warm air mass is caught between 2 cooler air masses; cool air flows under warm; as warm air cools and its water vapor condenses, the weather may turn cloudy and rain or snow may fall (weather cloudy and wet)


swirling center of low air pressure; winds spin counterclockwise inwards towards center; bring clouds, wind, precipitation


swirling center of high air pressure; winds spin clockwise, outward from center; brings dry clear weather


a violent disturbance in the atmosphere; sudden changes in air pressure, causes rapid air movement


a small storm often accompianed by heavy precipitation and frequent thunder and lightning; form in large cumulonimbus clouds called thunderheads


a sudden spark or electrical discharge, as these changes jump between parts of a cloud, between nearby clouds, or between a cloud and the ground


the sound of the explosion from when the air expands because of lightning

Thunderstorm safety

____________: avoid places where lightning can strike and objects that conduct electricity


a rapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to reach earth's surface

Tornado safety

_______________: a storm shelter on the basement of a well-built building is the best place for protection; stay away from windows and doors, lie under a sturdy object; if outside-lie in ditch


a tropical cyclone that has winds of 119km per hour or higher; form in atlantic pacific indian oceans

how hurricanes form

begins over warm ocean water as a low pressure area, or tropical disturbance; if tropical disturbance grows in size and strength, it becomes a tropical storm hurricane

Hurricane safety

_____________: evacuate

hurricane watch

hurricane conditions are possible in the next 36 hours

hurricane warning

hurricane conditions are expected in the next 24 hours


severe snowstorms, accompanied by high winds, low temps, low visibility

Blizzard safety

_____________: seek shelter, cover exposed parts of body, stay dry, car- keep exaust pipe clear


scientists who study the causes of weather and try to predict it- use maps, charts, and computers to analyze data and make forecasts

weather balloon

carries an instrument high into the troposphere and lower stratosphere to measure temp, air pressure and humidity


orbit in exosphere; make images of earth's surface, clouds, storms, snow cover

weather maps

shows location of fronts and areas of high and low pressure


lines joining points of equal pressure


lines joining points of equal temperature

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