Air Masses and Fronts

1. Air Masses and Fronts Chapter 20

2. Air Masses • Huge section of air that has the same weather throughout • Take on the characteristics of the area they originated over • maritime tropical – mT • continental tropical – cT • maritime polar – mP • continental polar - cP

3. Air Mass Source Regions

5. Air Masses • As an air mass moves, it takes on the characteristics of the region it covers • Marine air masses lose moisture as they travel across continental areas • Temperatures change as mass moves from cold  warm or warm  cold

6. Continental Polar • Cold and Dry in Winter • Cool and Dry in Summer • Can cause lake effect snow • Warm lake water adds moisture and becomes unstable

7. Continental Tropical • Least influence on North America • Hot and Dry • Originates in SW USA and Mexico • Rarely causes weather change outside its source

8. Maritime Polar • Cold and Wet • Sourced in the North Pacific • Low Clouds and Showers • Heavy Snow as air is lifted against mountains on the West Coast • Cause Nor’easters on the East Coast

9. Maritime Tropical • Strong influence on weather in North America • Warm, Wet and Unstable • Most of the rain in Midwest and East Coast from mT air mass. • Mixed with Continental Polar to produce thunderstorms and tornadoes