Air Masses
Diagram that shows the location of air masses as well as characteristics on each type.

What is an air mass?

An air mass is a large body of air that has a similar temperature and moisture content. They cover many thousands of miles, and are classified by latitude and their sources.

An air mass needs to have two conditions to form; the air must stay in the same source region for a period of time long enough for it to be able to take on characteristics of a region, and secondly the air has to be stable.

Air masses take on characteristics based on where they formed, for example if one formed over water it would have a higher moisture content than a mass formed over land.

There are many different types of air masses, based on there temperatures and where they originate. Such as Maritime polar, continental polar, maritime tropical, continental tropical, and continental Arctic.

Each air mass is responsible for different forms of weather, and temperatures. For example continental polar air masses are very cold with little moisture in them.
Different air masses and their location within North America.