Air Masses

Air Masses

There are many components when it comes to understanding different types of

weather systems. When it comes to weather, many vital parts such as air masses are very important to understand. One might ask, what is an air mass? An air mass is a large body of air that has similar temperature and moisture properties (ww2010.atmos.uiuc.edu).

When there are similar characteristics and temperature and humidity within an air mass this is called its source region. The source region is the original start of an air mass. For a source region to have similar characteristics, the surround environment must be of one. Also, there must be enough time for the source region to acquire the similar characteristics (Gabler). Some characteristics to determine a source region must be flat terrain, little wind and high pressure (www.uwsp.edu). There are six main types of air masses which are abbreviated by a first lower case letter and followed by a upper case letter. Gabler distinguishes the difference of each letter and each mass will be described.

There are only 2 lower case letter to choose from the first being m, meaning maritime. Maritime means the air mass originates over the sea and is relatively moist. The other choice is c, meaning continental. Continental means the air mass originates over land and is therefore dry (Gabler). The following uppercase letter helps locate the latitude of the source region. There are four uppercase letters to help distinguish the regions, E,T,P,A. E stands for equatorial like the equator, the conditions are warm. T stands for tropical and its origins are the tropics so this is warm as well. P is for polar where the conditions can be quite cold and lastly is A which stands for Arctic air and is really cold.

The following description of the different type of air masses will be concentrated more towards the air masses located in the United States and Canada but maps will be provided to show a globe perspective of the air masses as well as a more in depth chart on the air masses such as characteristics, accompanying weather and the source region.

Continental arctic air masses, cA, (60°-90° N) (www.uwsp.edu) are very frigid and the frozen surface of the Arctic Ocean serves as the source region for this air mass. The conditions are very cold, very stable and very dry. Most of the time cA doesn’t extend far enough to reach the Unites States but if so, the results can be damaging to vegetation. Most locations of this type of air mass are: the arctic ocean, Greenland, Antarctica, Alaska and Canada. The result of cA reaching the Midwestern to southeastern parts of the Unites States can be very seldom and record temperatures can often result (Gabler).

Continental polar air masses ,cP, (40°-60° N or S) (www.uwsp.edu) are about the northern part of the United States. Locations of these types of masses are plains and plateaus of sub polar and polar latitudes. The conditions are subsiding and stable air. In the winter the air is cold, dry, clear and crisp. On rare occasions, a sliver of the cP can reach the Gulf of Mexico and some parts of Florida. This type of mass usually will stay on the east part of the United States due to atmospheric circulation but if it were to make it far west as Washington, California and Oregon it can cause great agriculture damage (Gabler).

Maritime