AN AIR MASS IS A HUGE BODY OF AIR IN THE TROPOSPHERE, UP TO 2000KM IN DIAMETER, HAVING SIMILAR PRESSURE, MOISTURE, WIND, AND TEMPERATURE, CHARACTERISTICS.

AN AIR MASS IS A HUGE BODY OF AIR IN THE TROPOSPHERE, UP TO 2000KM IN DIAMETER, HAVING SIMILAR PRESSURE, MOISTURE, WIND, AND TEMPERATURE, CHARACTERISTICS THROUGHOUT.

Aim: What is an air mass and what factors determine its characteristics?

Characteristics of Air masses

Air mass Origin Weather Condition

mT (maritime tropical)

mP (maritime Polar)

cT (continental tropical)

cP (continental Polar)

cA (continental Arctic)

Tropical seas, Pacific and Atlantic Oceans, and Gulf of Mexico

Warm and moist, cloudy, rain and thunderstorms.

Pacific and Atlantic Oceans near Polar regions

Cold and moist, cloudy, rain or snow

Desert areas of southwestern U.S and Mexico

Clear, hot, and dry

Canada and northward

Clear, cold, and dry

Ice- covered Arctic regions Very cold and dry

Air Masses:

• large bodies of air that have homogeneous physical properties (temp. and humidity)

• air masses formin areas of stagnant air flow, where they can remain long enough to acquirethe conditions of thatregion

• winter air mass patterns for North America

• summer air mass patterns for North America

• cP air massesare associated withfrigid winter temps.that affect theeastern 2/3 of NorthAmerica

BBC Canada

• typical weather map showing eastern 2/3 of North America dominated by a cP air mass (note: anticyclone)

• air mass symbols k and w are added when an air massmoves over a surface that is different from its source region

k—air mass is colder than the surface it is passing over often leads to instability

warmer

Colder

w—air mass is warmer than the surface it passes over may lead to stability, inversions, and fog

warmer

colder