The atmosphere of our planet is the air envelopeEarth, protecting the surface from the deadly impact on all living ultraviolet rays of the Sun. In addition, the atmosphere prevents the penetration of dust and meteorites from outer space.
Atmosphere structure: composition
The protective shell consists of a mixture of gases:two-thirds of its volume is occupied by nitrogen, one-fifth is oxygen, and one percent is inert gases (krypton, argon, helium, and others). The volume of nitrogen and oxygen is almost unchanged, since nitrogen practically does not react with other substances and compounds, and oxygen, despite expenditure, is constantly replenished by plants.
Up to a 100-kilometer height, the ratio of these gases in percent does not practically change. This is due to the constant mixing of air masses.
In addition to the described components, the composition of the atmosphereincludes about 0.030 percent of carbon dioxide, which is concentrated closer to the earth's surface. Most of it in industrial centers, cities, in areas of volcanic activity.
Also the atmosphere includes in its structurea small amount of dust and water vapor. The volume of the last component depends on the ambient air temperature: when increasing, more vapor forms. The presence of water in the air in the vapor state makes it possible to observe such natural phenomena as refraction of the sun's rays, a rainbow, etc.
Dust entering the atmosphere occurs during eruptions of volcanoes, dust and sand storms, as a result of incomplete combustion of fuel at thermal stations.
The density of the air envelope is not the same everywhere.The height of the atmosphere influences this index. The densest shell at the surface of the planet, and with height it becomes less frequent. Already at a distance of 11 km the atmosphere is 4 times less frequent than in the surface layer.
Atmosphere structure: vertical section (stratification)
Depending on the properties of the gas, composition and density, the air shell is divided into 5 main parts - concentric layers.
The lowest layer is the troposphere, the upperthe boundary of which is at a distance of 10 km from the surface of the planet at the equator, at the poles this figure is 18 km. The bottom layer contains practically the entire water gas and almost 80 percent of the total volume of the atmosphere.
In the troposphere with altitude, the air temperature decreases: every hundred meters it becomes colder by 0.6 degrees, and at the upper boundary there is minus 45-50 degrees.
In this shell, there is a constant movement of air, which moves and mixes. Only here there are rains, there are thunderstorms, fogs, storms or snowfalls.
The second layer, which is part of the atmosphere,is the stratosphere, which extends to a height of 55 km. This shell has low pressure and air density. The rarefied masses consist of the same gases as the troposphere, however, there is more ozone here. The maximum concentration of this isotope of oxygen is observed at a distance of 20-30 km from the surface. The temperature of the stratosphere increases with altitude, and at the upper boundary this figure is 0 degrees. This is explained by the absorption of the short-wavelength part of the solar energy by ozone, which causes the heating of the air.
Above the stratosphere is the mesosphere, the heightwhich is 80 km from the surface. Here again, the temperature drops to minus 90 degrees at the upper boundary, the air density is two hundred times less than in the surface layers of the planet's atmosphere.
The distance from 80 to 800 kilometers isThe mesosphere is the fourth shell that enters the structure of the atmosphere. Here the gases are in the ionized state, and the temperature at the altitude of 160 km is 200 degrees, and at 650 km it reaches 1500 C. Here, electric currents are formed that act on the magnetic field, and polar auroras occur.
The last outer shell is called the exosphere,which is located above 800 km. Here the velocity of the particles reaches a critical level at which they can escape into space, breaking the earth's gravity.
