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Frontal Systems. Section 15.2. Fronts. Air masses move due to worldwide wind currents . The zone between air masses is called a front. Cold Fronts. This zone is formed where a moving cold air mass overtakes a warmer air mass.
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Frontal Systems Section 15.2
Fronts • Air masses move due to worldwidewindcurrents. • The zone between air masses is called a front
Cold Fronts • This zone is formed where a moving cold air mass overtakes a warmer air mass. • The cold air is more dense than the warm air. It moves below the warm air and pushes the warm air upward, making clouds – often making rain. • Fast moving fronts can cause intense thunderstorms which are often accompanied by hail and even tornadoes.
Warm Fronts • This zone is formed where a warm mass overtakes a cooler one. The warm air gently rides up over the trailing end of the cold air mass. • Clouds form, bringing light rain or snow. • Precipitation may last much longer than it does at a cold front but the temperature will be warmer than before the warm front arrived
Low Pressure Systems • Where air rising in a counterclockwise direction creates a cyclone and leaves less dense air below. • Low pressure systems usually bring unstable weather conditions such as precipitation and storms • They develop with a front (between air masses)
High Pressure Systems • Where air descends (putting pressure on the ground below) in a clockwise direction – called an anticyclone. • High pressure systems bring clear skies with little moisture. • They can last several days