What is the primary feature of a polar air mass?

The primary feature of a polar air mass is characterized by cold temperatures. Polar air masses originate from high-latitude regions, where they are formed over cold surfaces such as ice and snow. This results in their defining trait of being significantly colder than the air masses that form in lower latitudes, such as tropical air masses. Consequently, when polar air masses move into other regions, they often bring a drop in temperature and can influence weather patterns significantly.

In contrast, an air mass with high humidity is more typical of maritime origins, particularly tropical air masses, where warmer ocean waters contribute to moisture. Strong winds can occur in various types of air masses but are not a defining characteristic of polar air. Low pressure can be associated with weather systems influenced by polar air masses, but it is caused by other atmospheric dynamics rather than the air mass itself being low-pressure. Thus, cold temperatures are the defining and primary feature of a polar air mass.