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Jet Streams, Air Masses & Fronts

High in the atmosphere, jet streams act like narrow rivers of wind encircling the globe. Jet streams have a great impact on our climate as they push around air masses and affect the patterns of weather. As the jet stream changes its intensity and position, it affects the strength and motion of  air masses.

An air mass is a large body of air that has the same properties as the surface over which it develops (dry, hot, moist, etc). Air masses are classified by both humidity and temperature.

The types of air masses are based on these root words:

1.     Maritime-a wet/humid air mass that forms over oceans
2.     Continental-a dry air mass that forms over land
3.     Tropical-a warm air mass with low pressure that forms in the tropics
4.     Polar- a cold air mass with high pressure that forms in the northern Latitudes
5.     Arctic or Antarctic- very cold air mass that forms over the highest latitudes    

These root words may be combined in different ways to describe air masses. The first word describes where it is formed and if it is wet or dry and the last word tells us if it is warm or cold. Here are some examples:

1.     Maritime tropical- wet/humid and warm, formed over water
2.     Continental tropical- dry and warm, formed over land
3.     Maritime polar- wet/humid and cold, formed over water
4.     Continental polar- dry and cold, formed over land
5.     Continental Arctic or Antarctic - dry and very cold, formed over land

The place where air masses meet forms a boundary called a front.