Air Masses and Fronts

Air Masses Air mass: huge body of air that has similar pressure, humidity, and temperature Maritime (m) : Forms over water (moist) Continental (c): Forms over land (dry) Tropical (T): Forms in the tropics (warm) Polar (P): Forms in polar regions (cold) Acquires characteristics of that surface.

For example… don’t write this! If the source region is the gulf of Mexico and the air comes to Long Island… If it comes from central Canada…

Don’t write this 

Low Pressure and High Pressure Systems Lowest pressure in the center CCW due to coriolis effect

Wind blows TOWARD the center Counterclockwise Causes clouds/rain/wind Low Pressure Systems: Cyclones Wind blows TOWARD the center Counterclockwise Causes clouds/rain/wind Lowest pressure in the center Clockwise due to Coriolis Effect

High Pressure Systems: Anticyclones Wind blows AWAY FROM the center Clockwise --Clear, dry, sunny conditions highest pressure in the center CW due to coriolis effect

How Air Masses Move in the US Prevailing Westerlies Jet Streams Fronts

Fronts

Cold Front A fast-moving COLD air mass that overtakes a warm air mass Short period of heavy rain

Warm Front A WARM air mass overtakes a slow-moving cold air mass Gentle rain for a longer time

Occluded Front A warm air mass is caught between two cooler air masses

Stationary Fronts Cold and warm air masses meet, but neither moves the other