What is an air mass?

An air mass is defined as a large body of air that exhibits uniform properties in terms of temperature and humidity. This means that the characteristics of the air mass remain consistent over a significant area, influenced by the region from which it originates, such as over oceanic or continental areas. The characteristics of an air mass can directly affect the weather in the regions it moves into, making it a crucial concept in meteorology.

While the other options refer to important atmospheric phenomena, they do not capture the essence of what an air mass is. Weather phenomena can be influenced by air masses, but they are not synonymous with them. Specific measurements of air pressure pertain to individual atmospheric conditions rather than to the broader concept of an air mass. Lastly, although an air mass is indeed a component of the atmosphere, this description is too vague and does not emphasize its defining characteristics as a uniform body of air.