In meteorology, what does the term "air mass" refer to?

The term "air mass" in meteorology refers to a large volume of air that has relatively uniform temperature and moisture characteristics. Air masses form when air settles over a particular region for an extended period, gaining the properties of the underlying surface. These properties influence local weather patterns and can lead to different types of weather phenomena.

For instance, when warm and moist air masses move into a cooler area, they can produce thunderstorms or rainy conditions. Conversely, cold and dry air masses can lead to clear skies and cooler temperatures. Understanding air masses is crucial for predicting weather changes and understanding the dynamics of the atmosphere. The other options do not accurately capture the definition of an air mass: bodies of water relate to hydrology; high atmospheric pressure refers to a weather system that influences air movements but does not define an air mass; and cloud types describe specific atmospheric formations rather than broad characteristics of air itself.