The Earth's atmosphere consists of several parts,having a different composition. Stratosphere, exosphere, troposphere, ionosphere and other layers protect all life on the planet from hard cosmic radiation. Not all of them have in their composition oxygen in an amount sufficient for breathing. But each performs its functions. For example, the ionosphere is the uppermost layer of the atmosphere, located above 50 kilometers. It is named so because of the large number of ions formed due to the action of solar radiation. They are the ones that detain most of the cosmic radiation.
Ionosphere: composition
This layer of the atmosphere consists of a mixture of gases.They are very few there, so they say about very discharged air at this altitude. That's why flights in this place are impossible. Most of the Earth's ionosphere contains neutral atoms of nitrogen and oxygen. But its main composition is a quasineutral plasma in which the number of positively charged particles is approximately equal to the amount of negatively charged particles. Such ions become more and more with distance from the Earth. Therefore, the ionosphere is sometimes called the plasma shell of the Earth.
The main composition of the ionosphere from 50 to 100 kilometers above the surface of the Earth is oxygen, nitrogen and sodium. But after 100 km, hydrogen and helium begin to predominate in it.
Explanation of the name
The ionosphere is a layer of the atmosphere, called sobecause of the high degree of ionization. Its source is X-ray and ultraviolet solar rays. Ions are negatively charged electrons. In the ionosphere, their concentration is very high. The ion level is slightly influenced by the Earth's magnetosphere. But the amount of ionized electrons most often increases during flares on the Sun, and also because of the passage of various cosmic bodies, for example, meteorite particles, past the Earth. At night, when there is no solar radiation, the level of ionization is affected by galactic cosmic rays.
Outbreaks on the Sun lead to the fact that to the Earththe flow of elementary particles - protons, electrons - is directed. They affect all layers of the Earth's atmosphere. But most of the hard radiation is delayed in the ionosphere. At the same time, its ionization sharply increases.
Study of the ionosphere
This layer of the atmosphere was discovered in the early 20thcentury scientists E. Appleton, M. Barnet, G. Breit and M. Tewom. They found that at an altitude after 50 kilometers there is a layer of gases reflecting radio waves. They began to watch him. It was found that the ionosphere is constantly different. Even during the day, its composition and other characteristics are changing. A different number of gases are also in dependence from altitude. Therefore, the ionosphere was divided into three layers.
But a complete picture of the peculiarities of thisparts of the atmosphere, mankind was able to get only in the second half of the 20th century. We studied it from terrestrial ionospheric stations. Then they began to examine it from the inside. At first rockets, then satellites ascended to the upper atmosphere. And people could understand what the ionosphere is. Its composition was studied through the use of rockets from a mass spectrometer. This also made it possible to measure other parameters:
- temperature;
- ion concentration;
- electrical conductivity;
- sources of ionization;
- features of hard solar radiation.
Explore the ionosphere also using radio methods- study of reflected radio waves. And recently satellites began to be used, on board which there are stations and probes exploring the ionosphere from above. This made it possible to form an idea of its uppermost layer, inaccessible to study from the Earth.
Ionospheric layers
This part of the atmosphere is also heterogeneous. It distinguishes three layers with different degrees of ionization and gas density.
- In the lowest layer, extending to 90kilometers, ionization is the lowest. The air here is ionized under the influence of magnetic storms of the Earth, and also with the help of X-rays of the Sun. Therefore, at night, ionization here is further reduced.
- The second layer ranges from 90 to 120 kilometers.It is characterized by an average ion density, which rises strongly during the daytime under the influence of solar radiation. In this layer, medium and short radio waves are reflected. This part of the ionosphere is also called the Kennel-Heaviside layer, which first studied it.
- The rest of the ionosphere is above 130 kilometersis the third layer. The maximum level of ionization here is observed at an altitude of about 200 kilometers. This layer makes it possible to transmit short-wave radio emission over long distances. This layer was opened by the English physicist Appleton.
What is the ozone layer?
Below the ionosphere is the ozone layer.It protects the Earth from the harmful effects of ultraviolet rays and heat loss. Scientists have proved that ozone is useful for all living things. Reducing its number or total absence negatively affects the health of people. Ozone holes, which were discovered in the late 20th century, cause an increase in the number of cancers. Some scientists associate such processes not with the emission of gases from the Earth's surface, but with the destruction of the upper ionized layers of the atmosphere, which began to transmit harmful ultraviolet radiation.
Influence of the ionosphere on radio communication
A high degree of ionization of air in this layeratmosphere can affect radio communication. Negatively charged particles, chaotically moving, can change the direction of radio waves and even absorb their energy. As a result, there are strong interference, the temporary disappearance of radio communications, or, conversely, the enhancement of the diversity of distant radio stations.
Scientists have proved that it is the ionosphere - this is thelayer of the atmosphere, which makes possible the propagation of radio waves. It so happened that thanks to these waves, this layer was discovered in the 1920s.
For more accurate transmission of radio waves to distantdistance must be found in the ionosphere of the refractive point, reflected from which they fall exactly in the place in which it is needed. The problem is also that some of the energy is absorbed by negatively charged ions. This is associated with a phenomenon where long waves quickly decay in the ionosphere, and are better transmitted short. In addition, radio communication deteriorates during magnetic storms, in which ionization decreases.
Destruction of the ionosphere
Everybody knows why the Earth needs an atmosphere.The ionosphere is its layer, which protects the remaining layers from hard cosmic radiation. Therefore, it is very important that its composition is maintained at a normal level. But human activity in recent years leads to the fact that this layer of the atmosphere begins to collapse. For example, when launching the Skayleb Space Laboratory, a huge amount of hydrogen is released into the ionosphere.
Other launch vehicles affect compositionatmosphere. Space Shuttle emits a large amount of chlorine, carbon monoxide, aluminum oxide, hydrogen when burning fuel. A RN Energia is a lot of nitrogen oxide. All this actively destroys the layers of the ionosphere and leads to a decrease in the amount of ozone. The remains of fuel have accumulated for a long time in the upper atmosphere. Especially a lot of them contain the stratosphere. The ionosphere is very sensitive to changes in its composition, so the ions are rapidly destroyed.
It turns out that when launching spacecraftalong the entire route of their flight, a corridor, the so-called ionospheric hole, is formed. At this point cosmic rays can penetrate the atmosphere and reach the Earth's surface, adversely affecting all living organisms.
Northern Lights
The ionosphere is the place where such aAn amazing phenomenon, like the northern lights. It arises under the influence of radiation from outer space. When charged cosmic particles moving toward the Earth enter the upper layers of the ionosphere, an ion perturbation arises that is perceived from below as a beautiful iridescent glow. In fact, this process is a neutralization in the ionosphere of vortices of charged particles coming from the Sun. If not for this layer, the "solar wind" would destroy all life on Earth.
