If the air over an extensive territory has the same humidity and temperature, it is called an air mass. In zones of the formation of these masses distinguish between polar air mass and tropical air mass. They are called sea air, if formed over the ocean or seas, and continental, if formed over the continents. For example, there is a polar Maritime air or tropical Maritime air, tropical continental air or polar continental.
These air masses have a huge impact on weather. They move, cooled or heated and become drier or wetter - depending on what areas are.