What term describes the mass of air surrounding the Earth?

The term that describes the mass of air surrounding the Earth is "atmosphere." The atmosphere is a layer of gases that extends from the surface of the Earth to outer space. It plays a critical role in supporting life by providing essential elements such as oxygen, protecting living organisms from harmful solar radiation, and regulating temperature through the greenhouse effect.

In contrast, the hydrosphere refers to all the water on Earth, including oceans, rivers, lakes, and water vapor; the biosphere encompasses all living organisms and their interactions with the environment; and the lithosphere pertains to the solid outer part of the Earth, including the crust and the upper mantle. Each of these terms describes a different component of the Earth's system, but only the atmosphere specifically addresses the mass of air.