How are air masses primarily categorized?

Air masses are primarily categorized based on their temperature and moisture characteristics. This classification helps meteorologists understand and predict how these air masses will influence weather patterns as they move across different regions. Temperature is crucial because it indicates whether the air mass is warm or cold, while moisture content indicates whether it is dry or humid. For instance, an air mass originating from a polar region is typically cold and dry, whereas one from a tropical region is warm and moist. The combination of these two aspects determines the air mass's behavior and its potential impact on weather patterns, such as precipitation and temperature shifts.

The other options focus on different characteristics that do not primarily define air masses. While altitude and pressure are important in meteorology, they relate more to atmospheric layers and weather fronts rather than the categories of air masses. Wind speed and direction are also significant, especially for understanding weather movement, but they are not used to categorize the air masses themselves. Lastly, geographic location can give context to an air mass's origin, but it does not provide the same direct indication of its temperature and moisture characteristics.