Overview
This lecture introduces air masses, their classification system, and the characteristics of major air mass types impacting weather and climate.
Definition and Classification of Air Masses
- An air mass is a large parcel of air in the troposphere with uniform temperature, density, and humidity.
- Air masses can span thousands of miles horizontally.
- Classification uses letter codes reflecting surface type and source region.
Air Mass Letter Codes
- Lowercase 'm' stands for maritime (forms over water, moist).
- Lowercase 'c' stands for continental (forms over land, dry).
- Uppercase 'T' stands for tropical (forms in tropics, warm/hot).
- Uppercase 'P' stands for polar (forms in polar regions, cold).
- Uppercase 'A' stands for arctic (forms in high-latitude polar regions, extremely cold).
Major Types of Air Masses
- mP (Maritime Polar): Cool and wet; forms over high-latitude oceans.
- cP (Continental Polar): Cold and dry (especially in winter); forms over high-latitude continents.
- cT (Continental Tropical): Hot and dry; forms over low-latitude land areas (deserts).
- mT (Maritime Tropical): Hot and humid; forms over tropical oceans; brings sultry weather.
- A (Arctic or Continental Arctic): Extremely cold and dry; forms over frozen arctic regions; responsible for events like the Texas freeze.
Distribution and Impact
- Air masses are distributed globally according to surface type and latitude.
- The movement of air masses affects regional weather and climate patterns.
- mT and cT influence humid and dry conditions, respectively, in the tropics.
- Polar and arctic air masses affect colder climates and can cause extreme weather events.
Key Terms & Definitions
- Air Mass — Large body of air with uniform temperature and humidity.
- Maritime (m) — Forms over water, resulting in moist air.
- Continental (c) — Forms over land, resulting in dry air.
- Tropical (T) — Refers to low-latitude, warm regions.
- Polar (P) — Refers to high-latitude, cold regions.
- Arctic (A) — Extremely high-latitude, very cold regions.
Action Items / Next Steps
- Review the map showing global air mass source regions.
- Prepare for the next video on mechanisms of cloud formation.