Air Pressure and Weather Systems

Air pressure will decrease when there is an increase in...
Altitude
Humidity (dry air more dense)
Temperature (cold air more dense)

On a map;
Isobars are used to show ares that all share the same pressure reading

Air pressure is measured with a barometer
An increase in atmospheric pressure pushed the mercury up the tube











If there is a drop in barometric pressure (air pressure) then clouds and precipitation will follow

If there is an increase in barometric pressure (air pressure) then fair weather will follow

Weather Systems:
High Pressure;
Marked by a H on the map
Winds travel clockwise and air moves outwards away from center
Sinking air prevents cloud formation and precipitation= fair weather

Low Pressure;
Marked by a L on the map
Winds travel counterclockwise and air moves toward center
Sign that a front is coming
Warm, moist air rises (less dense) forming clouds and precipitation