1. 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?

2. Characteristics of Air masses Air massOriginWeather 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 northwardClear, cold, and dry Ice- covered Arctic regionsVery cold and dry

3. Air Masses: large bodies of air that have homogeneous physical properties (temp. and humidity ) air masses form in areas of stagnant air flow, where they can remain long enough to acquire the conditions of that region

4. winter air mass patterns for North America summer air mass patterns for North America

5. cP air masses are associated with frigid winter temps. that affect the eastern 2/3 of North America BBC Canada

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

7. air mass symbols k and w are added when an air mass moves 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