Air is matter that has weight and contains 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of argon, carbon dioxide and other ingredients.Continue Reading
Air is a mixture of gases, which is why it has weight. Gases are a composition of several molecules that remain in constant motion. It occupies volume in space, but how much space it takes up depends on its temperature. Normally, gases at a higher temperature take up more space.
Air's density varies in different parts of the atmosphere. At the edge of space, its density is zero. Air density, temperature and pressure can change several times per day and varies from region to region.Learn more about Atmosphere
In dry air that does not contain pollution, the predominant gas is nitrogen, which makes up 78 percent of the atmosphere. The next two most voluminous gases are oxygen (21 percent) and argon (1 percent). Other gases appearing in trace amounts include carbon dioxide.Full Answer >
The gas that makes up about 21 percent of the atmosphere is oxygen. The atmosphere surrounding the Earth is not the same as it once was, as oxygen was not nearly as abundant.Full Answer >
Air seems thinner at high altitudes because air pressure is lower, which allows individual air molecules to occupy a larger volume than air molecules do at low altitudes. This decreasing pressure with increasing altitude occurs because there are increasingly fewer air molecules exerting pressure on the next-lowest altitude.Full Answer >
Air cools when it rises through the atmosphere because as altitude increases, air pressure decreases and allows the individual air molecules to expand away from each other. This expansion leads to a decrease in collisions between air molecules, which then results in less heat energy being transferred between those molecules.Full Answer >