This is what the air is made of
is used to move air
Air is the Earth's atmosphere. Air around us is a mixture of many gases and dust particles. It is the clear gas in which living things live and breathe. It has an indefinite shape and volume. It has no colour or smell. It has mass and weight, because it is matter. The weight of air creates atmospheric pressure. There is no air in outer space.
Air is a mixture of about 78% nitrogen, 21% oxygen, 0.9% argon, 0.04% carbon dioxide, and very small amounts of other gases. There is an average of about 1% water vapour.
Animals live by aerobic respiration and need to breathe the oxygen in the air. In breathing, the lungs put oxygen into the blood, and send back carbon dioxide to the air. Plants need the carbon dioxide in the air to live. They give off the oxygen that we breathe. Without it we die of asphyxia.
Wind is moving air. This causes weather.
Air can be polluted by some gases (such as carbon monoxide), smoke, and ash. This air pollution causes various problems including smog, acid rain and global warming. It can damage people's health .
Aircraft use propellers to move air over a wing, which allows them to fly. Pneumatics use air pressure to move things.
- ↑ "composition of air".
- ↑ Zimmer, Carl (3 October 2013). Earth’s Oxygen: a mystery easy to take for granted. New York Times.