Air is a substance that can be measured weighed, dissolved, condensed, frozen, and even seen when it is trapped below water or when it is liquefied.
Air has weight, and as a result, it exerts a pressure on everything around it, operating in all directions. Air pressure is measured with a barometer.
The Earth's atmosphere protects the planet from radiation, and also from the surface impact of most cosmic of the material that reaches the planet.
Global systems drive the weather on the whole planet, both in the short term of a few days, and also by seasons and several multi-year patterns.
There are a number of recognized levels in the atmosphere, and these levels include the troposphere, the stratosphere the mesosphere and the ionosphere.
Air is made of individual gases, each of them exerting a partial pressure on everything around them. Oxygen, nitrogen and noble gases make up most of the air.
Air is largely transparent, but it can be seen on very hot days, when you look along a hot surface, and see a heat shimmer caused by air of varying density.
At sea, wind speed is measured on the descriptive Beaufort wind scale, and at other times, it is measured in knots, one of the few universal non-SI units.
Chlorofluorocarbons (CFCs) are effective refrigerants, but when they escape, they cause ozone depletion in the upper atmosphere by reacting with the ozone.