Air Pressure & Fronts

Air Pressure The force pushing down on an area Decreases as you go up (mountain) Changes in pressure result in wind Measured with a barometer 970 millibars – 1040 millibars

High Pressure Systems Air tends to sink Air moves outward (clockwise) Usually clear skies Gentle breezes Air moves outward (clockwise)

Low Pressure Systems Air tends to rise Clouds Storms Wind Air moves inward (counter-clockwise) Low pressure systems tend to have fronts associated with them

Air Mass Large volume of air with consistent temperature and moisture content Depends on where it originates Air masses are separated by fronts

Fronts Cold Front  Warm Air Warm Front  Cold Air Stationary Front Can produce short-lived thunderstorms Warm Front  Cold Air Long, steady rains Stationary Front Not much movement Occluded Front Thunderstorms, Rain