The atmosphere of the Earth consists of several parts having different composition. The stratosphere, exosphere, troposphere, ionosphere and other layers protect all life on the planet from hard cosmic radiation. Not all of them have enough oxygen in their composition for breathing. But each performs its own functions. For example, the ionosphere is the uppermost layer of the atmosphere, located above 50 kilometers. It is so named because of the large number of ions generated due to exposure to solar radiation. It is they who delay most of the cosmic radiation.
Ionosphere: composition
This atmosphere layer consists of a mixture of gases. They are very few there, so they talk about very discharged air at such a height. That is why flying in this place is impossible. Most of the Earth’s ionosphere contains neutral nitrogen and oxygen atoms. But its main composition is quasi-neutral plasma, in which the number of positively charged particles is approximately equal to the number of negatively charged. There are more and more such ions with distance from the Earth. Therefore, the ionosphere is also sometimes called the plasma shell of the Earth.
The basic 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 prevail in it.
Name explanation
The ionosphere is a layer of the atmosphere, so named because of the high degree of ionization. Its source is X-ray and ultraviolet rays of the sun. Ions are negatively charged electrons. In the ionosphere, their concentration is very high. The ionosphere is slightly affected by the Earth’s magnetosphere. But the number of ionized electrons most often increases during flares on the Sun, and also due to the passage of various cosmic bodies, for example, meteorite particles, past the Earth. At night, when there is no solar radiation, galactic cosmic rays affect the level of ionization.
Flashes on the Sun lead to the fact that a stream of elementary particles — protons, electrons — is directed to the Earth. They affect all layers of the Earth’s atmosphere. But most of the hard radiation is delayed in the ionosphere. In this case, its ionization sharply increases.
Ionosphere study
This layer of the atmosphere was discovered at the beginning of the 20th century by scientists E. Appleton, M. Barnet, G. Breit and M. Tew. They found that at an altitude after 50 kilometers there is a layer of gases reflecting radio waves. They began to observe him. It was found that the ionosphere is constantly different. Even during the day, its composition and other characteristics change. Different amounts of gases are also dependent on altitude. Therefore, the ionosphere was divided into three layers.
But mankind could get a complete picture of the features of this part of the atmosphere only in the second half of the 20th century. We studied it from ground-based ionospheric stations. Then they began to examine it from the inside. First rockets, then satellites rose into the upper atmosphere. And people were able to understand what the ionosphere is. Its composition was studied due to the use of a mass spectrometer with rockets. It also allowed to measure other parameters:
- temperature
- ion concentration;
- electrical conductivity;
- ionization sources;
- Features of hard solar radiation.
The ionosphere is also explored using radio methods - the study of reflected radio waves. And recently, satellites began to be used, on board of which there are stations and probes exploring the ionosphere from above. This allowed us to get an idea of its uppermost layer, inaccessible to study from the Earth.
Ionosphere 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 up to 90 kilometers, ionization is the lowest. The air here is ionized under the influence of Earth's magnetic storms, as well as with the help of X-rays of the Sun. Therefore, at night, ionization here is even more reduced.
- The second layer ranges from 90 to 120 kilometers. It is characterized by an average density of ions, which increases greatly in the daytime under the influence of solar radiation. This layer reflects medium and short radio waves. This part of the ionosphere is also called the Kenneli-Heaviside layer, which first studied it.
- The rest of the ionosphere above 130 kilometers is 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 discovered 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 from heat loss. Scientists have proven that ozone is good for all living things. A decrease in its quantity or complete absence negatively affects people's health. Ozone holes, which were discovered at the end of the 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.
The influence of the ionosphere on radio communications
The high degree of air ionization in this layer of the atmosphere can affect radio communications. Negatively charged particles, moving randomly, can change the direction of radio waves and even absorb their energy. As a result of this, strong interference occurs, a temporary disappearance of radio communications, or, conversely, an increase in the sustainability of distant radio stations.
Scientists have proved that it is the ionosphere that is the layer of the atmosphere that makes the propagation of radio waves possible. It so happened that thanks to these radio waves this layer was discovered in the 20s of the 20th century.
For a more accurate transmission of radio waves over long distances, it is necessary to find refraction points in the ionosphere, reflecting from which they will get to exactly the place where you need to. The problem is also that part of the energy is absorbed by negatively charged ions. A phenomenon is associated with this, when long waves decay quickly in the ionosphere, and short waves are better transmitted. In addition, radio communications deteriorate during magnetic storms, during which ionization decreases.
The destruction of the ionosphere
Everyone 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 the Skyleb space laboratory is launched, a huge amount of hydrogen is released into the ionosphere.
Other launch vehicles no less affect the composition of the atmosphere. The space shuttle emits a large amount of chlorine, carbon monoxide, alumina, and hydrogen during fuel combustion. And the LV "Energy" - a lot of nitric oxide. All this actively destroys the layers of the ionosphere and leads to a decrease in the amount of ozone. Fuel residues have long accumulated in the upper atmosphere. Especially a lot of them contains the stratosphere. The ionosphere is very sensitive to changes in its composition, so the ions are rapidly destroyed.
It turns out that when launching spacecraft along the entire route of their flight, a corridor forms, the so-called ionospheric hole. 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 an amazing phenomenon as the northern lights forms. It arises under the influence of radiation from space. When charged cosmic particles moving toward the Earth enter the upper layers of the ionosphere, a disturbance of ions occurs, which is perceived from below as a beautiful iridescent glow. In fact, this process is the 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.