The atmosphere - a gas cover which is not only at Earth, but also at other planets and stars. The atmosphere of Earth differs in own unique parameters. Above it borders on near-earth space, below - on a lithosphere and the hydrosphere of Earth.
1. The atmosphere is a mix of several various gases which surround Earth and do possible existence of living organisms on the planet, protecting from a harmful range of sunlight and providing oxygen. In the atmosphere nitrogen (about 80%) and oxygen (about 19%) prevails. All other gases in total make less than one percent: it is carbon dioxide, helium, neon, argon, ammonia, krypton, hydrogen, methane, nitrogen oxides, water vapor.
2. The atmosphere includes several layers: troposphere, stratosphere, mesosphere, thermosphere, exosphere. The troposphere reaches height of 9-15 km over the Earth's surface. It is the warmest, the air layer heated by sunshine, its temperature falls in process of removal from the earth. Planes fly within the troposphere, almost all clouds as here a large amount of water vapor is concentrated are formed here. Troposphere height over different areas of Earth constantly fluctuates: minimum - over poles, maximum - over the equator. Weather and climate substantially are defined by the troposphere.
3. The stratosphere comes to an end approximately in 50 km and above from the Earth's surface. In its top part there is an ozone layer constraining harmful ultra-violet radiation therefore the stratosphere is so important for life on the planet.
4. The following layer - the mesosphere stretching to height of 70-80 km in its limits is located the coldest part of the atmosphere, temperature less than -200 °C here. Existence of the mesosphere saves the planet from meteors which burn down in this layer as contact of a meteor with molecules of oxygen creates very high temperatures.
5. The thermosphere is located at the height about 100-700 km. Its name is defined by extremely high temperatures. The thermosphere, in turn, is divided into an ionosphere and a magnetosphere. Ionization (receiving electric charge particles) in a consequence of influence of solar radiation creates an ionosphere. Thanks to it people have an opportunity to observe polar lights and also to use a radio communication. A magnetosphere, working as magnetic field, protects Earth.
6. The exosphere (or a dispersion layer) - an upper atmosphere, on average is at the height of 600-700 km though the lower bound constantly changes, and top within 2-3 thousand km. There the exosphere gradually passes into space. This layer consists of the rarefied ionized gas, and the distance between particles is very big.
7. It is accepted to allocate one more layer of the atmosphere - the biosphere, the area of existence of all live. In its borders - life of plants, animals and the person. Plants play an important role, participating in process of photosynthesis and providing the oxygen necessary for people and animals.