Scaffolded notes
Build the idea
Air masses form over broad, uniform regions
When air remains over a large land or water area, it can take on that surface's temperature and moisture characteristics. The first letter identifies moisture: continental (c) is dry and maritime (m) is moist. The second identifies temperature: tropical (T) is warm and polar (P) is cold.
Four common air masses affect the United States
Continental polar (cP) is cold and dry; maritime polar (mP) is cool and moist; continental tropical (cT) is hot and dry; maritime tropical (mT) is warm and moist. Arctic air can be even colder and drier.
Air masses change as they travel
An air mass can be modified by the surface below. Cold dry air moving across warm ocean water gains heat and moisture. Forecasts must consider both source characteristics and the path the air mass has traveled.
Stop and explain
Check your thinking
1. What does mT mean?
Possible response: Maritime tropical: warm and moist.
2. Which air mass often brings cold dry winter air from Canada?
Possible response: Continental polar, cP.
Interactive challenge
Try the science
Match each air mass to its core properties.
Before you leave
Exit ticket
Classify warm, humid air arriving from the Gulf or western Atlantic.