Definition
A classification of air mass that forms over large, hot, dry land areas in tropical or subtropical latitudes. Continental tropical air is hot and dry, with low humidity and generally clear skies, and is associated in North America with the desert regions of the southwestern United States and northern Mexico in summer.
Plain English
An air mass that picks up its character from sitting over hot, dry land in warm parts of the world. The result is hot, very dry air with little moisture and few clouds.
Context Anchor
Seen on weather charts and in weather-study material that describes North American air mass source regions.
Derivation
The lowercase 'c' stands for continental, meaning the air mass formed over land rather than water, so it is dry. The uppercase 'T' stands for tropical, meaning it formed in warm latitudes, so it is hot. The two-letter code is a standard meteorological shorthand: small letter for moisture source (continental or maritime), capital letter for temperature source (Arctic, Polar, or Tropical).
Why Pilots Care
cT air masses produce hot, dry conditions that can reduce visibility from haze or dust, create thermal turbulence, and influence thunderstorm development or stable clear skies.
Grounding Statement
Picture air sitting over a hot desert or dry inland region long enough to become hot and dry itself.
Intuition Check
Continental tropical does not mean moist jungle or island weather. In this label, continental means the air formed over land, so it is usually dry; tropical means it formed in a warm region.
Example Sentence 1
The briefer noted a continental tropical air mass over Arizona, so the pilot planned an early departure to avoid the worst density altitude later in the day.
Example Sentence 2
Forecasters tracked the cT source region over the desert and warned of reduced visibility from blowing dust along the route.