Final answer:
A wet and cold air mass is classified as humid, while a hot and dry air mass is classified as arid.
Step-by-step explanation:
An air mass that is wet and cold would be classified as a humid air mass. Humidity refers to the amount of water in the air, so air with a high concentration of water vapor is considered humid. Cold climates with low precipitation may not be as dry as warm climates with the same amount of precipitation.
On the other hand, an air mass that is hot and dry would be classified as an arid air mass. Arid climates are characterized by low moisture levels and little precipitation. These climates are often found in desert regions.