Air Masses of North America
Continental Polar/Arctic -
Stable, cold, dry air masses originating over N. Canada and Alaska
eventually plunge southward to interior of U.S. as a shallow dome of high pressure
can reach Gulf of Mexico and Florida - freeze crops
Produce lake effect snows as they move over the great lakes.
Usually do not move west of Rocky mountains - mountains confine cold air to the east.
Upslope precipitation is common east of the rockies as the cP air mass slides to the south
During the summer, cP air mass can bring relief to hot, humid regions.