The CT air masses are air masses that originate from deep inside the land masses in the tropical regions of the Earth. The ''C'' actually stands for continental, thus indicating the formation of the air mass over a land mass, while the ''T'' stands for tropical, thus indicating the tropical region of where the land mass over which this air mass forms.
Because these air masses form over land in the tropics, they are hot and dry. The hot and dry characteristics come from the bigger heating of the land masses, as well as the lack of water vapor over the land masses.
