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Understanding Air Masses and Their Effects

Sep 21, 2024

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.