Lecture Notes: Weather Types Based on Air Mass Characteristics

Key Concepts

• Air Masses: Large bodies of air with similar air and dew point temperatures.
  • Form over flat areas with similar surfaces and light winds.
  • Classified based on moisture and thermal characteristics.
  • Example size: Southeastern United States.

Classification of Air Masses

1. Moisture Characteristics

   • Maritime (M): Air masses forming over water. High dew point temperatures.
   • Continental (C): Air masses forming over land. Low dew point temperatures.

2. Thermal Characteristics

   • Tropical (T): Warmer air masses from the tropics.
   • Polar (P): Cooler air masses.
   • Arctic (A): Very cold air masses.

Common Air Mass Types

• Maritime Tropical (MT)

  • Warm and moist.
  • High air temperatures and high dew point temperatures.
  • Moves into the southeastern U.S. from the Gulf of Mexico.
  • Causes thunderstorms, especially during the Arizona monsoon.

• Continental Polar (CP)

  • Cold and dry.
  • Forms near the Canadian plains.
  • Moves southward, causing upslope precipitation and lake effect snow over the Great Lakes.
  • Can cool hot, humid conditions in summer.

• Maritime Polar (MP)

  • Cool and moist.
  • Often a modified CP air mass from Siberia.
  • Picks up moisture over the North Pacific.
  • Causes orographic precipitation on the windward side of the Olympic Mountains and the Cascades.

• Continental Tropical (CT)

  • Warm and dry.
  • Forms in the Four Corners region and West Texas in summer.
  • High air temperatures and low dew point temperatures.

Interactions and Effects

• Dry Line
  • Boundary where CT air mass meets MT air mass.
  • Dry air pushed over moist air, creating a vapor gradient.
  • Acts as a lifting mechanism for storm formation, typically in the afternoon.