The atmosphere is composed of gases, mainly nitrogen (78%), and oxygen (21%). Other gases found in the atmosphere and that make up approximately 0.99% of it are argon, helium, hydrogen, carbon dioxide, and water vapor. This gas composition usually remains fixed all around the world, but specific conditions may exist depending on the altitude, the seasons or the pollution.
Some of the atmosphere’s physical properties are (Sampieri, 2006):
Air has the ability to flow, especially on the layer closest to the surface. It moves horizontally, like the wind, or vertically because of the convective currents.
Air has no color, is transparent, we are submerged under a deep “ocean of gases”. The blue color of the troposphere, the inner layer of the atmosphere, is caused because the nitrogen and oxygen divert the blue color from the solar light, composed of several colors (red, yellow, orange, green, blue, and violet).
It is the physical property of a gas to decrease its volume when pressure rises.
It is the opposite of compressibility that is the gas ability to expand when the pressure decreases.
It is the atmosphere’s property by which sun rays cross and heat directly the Earth’s surface. That is why the atmosphere’s superior layers are cold, because the sun rays cross them and heat directly the lithosphere and the hydrosphere.
Among the atmosphere chemical properties are (Salinas, 2012):
Oxidizing agent. The atmosphere oxidizes substances because of the contained oxygen; this process can be seen in metals and rocks. It maintains combustion, because this reaction cannot be done without oxygen.
The atmosphere has 5 atmospheric layers, one of each having different gas compositions, temperature and heights.
It must be highlighted that, when height increases, the atmosphere’s density decreases. The atmospheric layers are the following (Salinas, 2012):