Air Masses

It is bitterly cold tonight, and one of the top news stories this week has been the weather across the entire country.  

Reference ACWM Chapter 6

Definitions:

• Air mass: a body of air whose temperature and humidity characteristics are uniform in the horizontal.
• Source region: a large area of land or ocean of relatively uniform characteristics and above which an air mass can form.
• Front: a transition zone between two air masses

Classification of Air Masses:

• Continental Arctic (cA)
• Maritime Arctic (mA)
• Continental Polar (cP)
• Maritime Polar (mP)
• Continental Tropical (cT)
• Maritime Tropical (mT)

Canadian Air Masses: cA, mA, mP, mT

Air masses may be modified as they migrate from their source regions.

• cold air (i.e. cA) moving south over the Lake Ontario in the winter becomes unstable since it is warmed from below, contributing to snow showers in Buffalo / south shores.
• warm air (i.e. mT) moving north over the Great Lakes in the spring becomes more stable since it is being cooled from below, contributing to stratus cloud, drizzle and fog over the north shores

POP QUIZ!

A south-westerly flow of Maritime Tropical air moving over the Labrador Current would produce what kind of fog?