Final answer:
Continental Tropical (cT) air masses impact the southwestern areas of the United States and Mexico, bringing hot and dry weather.
Step-by-step explanation:
Air masses that impact the southwestern areas of the United States and Mexico are labeled as Continental Tropical (cT) air masses.
Continental Tropical air masses are hot and dry and originate from the subtropical regions, such as the deserts in the southwestern United States. These air masses bring warm and dry weather to the region, contributing to the arid and semi-arid conditions in the American Southwest.
Other air masses, such as Maritime Tropical (mT) and Maritime Polar (mP), also influence weather patterns in different parts of the United States and Mexico.