1. Air Mass
A large body of air that take on the characteristics of the area over which it forms
Two main characteristics
Temperature
Tropical (warm, hot)
Polar (cool, cold)
Humidity
Maritime (moist)
Continental (dry)
Air mass modification – when an air mass moves, it changes to become more like the area to which is has moved

2. Air Mass Map
Source: Earth Science – Geology, the Environment, and the Universe, Interactive Chalkboard, (NC Edition), Glencoe Science, McGraw-Hill Companies

3. Fronts
Boundaries that form between air masses of different densities (temperature, pressure, and humidity)
Four kinds
Warm
Cold
Stationary
Occluded
See also -

4. Cold Front
Source: Earth Science – Geology, the Environment, and the Universe, Interactive Chalkboard, (NC Edition), Glencoe Science, McGraw-Hill Companies

5. Warm Front
Source: Earth Science – Geology, the Environment, and the Universe, Interactive Chalkboard, (NC Edition), Glencoe Science, McGraw-Hill Companies

6. Stationary Front
Source: Earth Science – Geology, the Environment, and the Universe, Interactive Chalkboard, (NC Edition), Glencoe Science, McGraw-Hill Companies

7. Occluded Front
Source: Earth Science – Geology, the Environment, and the Universe, Interactive Chalkboard, (NC Edition), Glencoe Science, McGraw-Hill Companies

8. Map symbols for fronts