what is an airmass?

• a large body of air with similar temp and humidity characteristics in any horizontal direction at any given altitude.

Arctic region

Continental

Arctic region

• land - extremely cold, dry stable

• ice and snow covered surface

Polar

• cold, dry, and stable over land

Tropical

• hot, dry, stable air aloft

• unstable surface air

Martime

Polar

• cool, moist, unstable

Tropical

• warm moist, usually unstable

Source regions

• should be flat and uniform

• strength of properties acquired by an airmass depends on its length of of stay in the source region

fronts

• boundary between two different air masses

Frontogenesis

• the formation of a front

• initial movement of an air mass

Frontolysis

• the death of a front

• modification of the air mass

FROPA

• Frontal Passage

What can a frontal analysis tell you?

• sharp temp gradient

• sharp moisture gradient

• shift in wind direction

• pressure pattern

• pressure changes

• cloud and precipitation patterns

what is a cold front?

• the boundary of an advancing mass of cold air.

• dome of dense cold air is replacing warm air.

• leading edge of the cold front is steep, leads to strong upward motion.

• warm air pushes up over cold air.

• convection is located at the leading edge of the cold front.

• has winds perpendicular to the front pushing the winds along.