Air is the mixture
of gases that surrounds the Earth. Air contains mainly the gases
nitrogen and oxygen, with small amounts of argon and other noble gases and carbon
dioxide. The proportions of these gases in air are the same anywhere around the
world. Air also contains water vapor, dust, and polluting gases, which vary in amount
from place to place. When air is cooled to -328°F (-200°C), most of the gases condense,
forming a blue liquid called liquid air. (Dictionary of Science, by Neil
Ardley)
Air is the mixture
of gases that surrounds the Earth. Air contains mainly the gases
nitrogen and oxygen, with small amounts of argon and other noble gases and carbon
dioxide. The proportions of these gases in air are the same anywhere around the
world. Air also contains water vapor, dust, and polluting gases, which vary in amount
from place to place. When air is cooled to -328°F (-200°C), most of the gases condense,
forming a blue liquid called liquid air. (Dictionary of Science, by Neil
Ardley)