"air" explained by:

	Three_quarter_ten (2 points with 2 valuations) Air is the mixture of gases that makes up the Earth's atmosphere. It is mostly nitrogen (about 78%) and oxygen (about 21%). We breathe air.

	Youser (1 point with 1 valuation) Layer of gases surrounding the planet Earth, retained by Earth's gravity. Protects life on Earth by absorbing ultraviolet solar radiation. » http://www.srh.noaa.gov/srh/jetstream/.../layers.htm

No responsibility is taken for the correctness of this information. All entries are licensed under Creative Commons CC-BY.