Air is a gaseous substance that is composed primarily of nitrogen, oxygen and argon. The air in the atmosphere that surrounds the Earth is approximately 78 percent nitrogen, 21 percent oxygen and 1 percent argon, with the remainder made up of various other gases including neon, helium and hydrogen.Know More
Although the proportion of gases found in air does not change as one moves further from the Earth's surface, the density of the air does. This means that there are fewer molecules of nitrogen, oxygen, argon and other gases a mile above the Earth's surface than an inch above it, but the same ratio of gases.
Some natural and unnatural non-gaseous particles are also found in the atmosphere, especially in the portions closest to the Earth's surface. These include volcanic ash, aerosol pollutants such as chlorine and mercury, pollen, and mold spores. The levels of these substances in the air tend to vary by location and with the seasons.
Air pollution is defined as the introduction of chemicals, particulate or biological matter into the air. This is typically considered a problem because it reduces the levels of ozone, an oxygen species, in the stratosphere. With less ozone in the atmosphere, the sun's harmful UV rays can more easily reach the Earth's surface, contributing to problems such as skin cancer and global warming.Learn more about Earth Science
In the nitrogen cycle, legumes form a symbiotic relationship with certain types of bacteria that are involved in a process known as "nitrogen fixation." The legumes provide the microorganisms with the required energy to initiate the process, while the bacteria fixes captured nitrogen from the air into a usable form, which is absorbed by the legumes for sustenance.Full Answer >
Lightning breaks apart nitrogen molecules. This allows the molecules to combine with oxygen and, together, they form nitrogen oxides. The nitrogen oxides dissolve in rain and form nitrates.Full Answer >
Air is invisible because it is a gas, and gas particles generally allow light to pass through them because they are so spread apart. Gases expand to fill any container they are in, as they do not hold a shape; therefore, it is usually easy to see through them.Full Answer >
Air is not a pure substance but a mixture of different gases. It is composed of approximately 78 percent nitrogen and 21 percent oxygen, with small amounts of about a dozen other gases making up the remainder.Full Answer >