It's no secret that air is an extremely important part of the biosphere. After all, it is its unique composition that provides the opportunity for life on the planet. But what is the name of the air shell of the Earth? What is it and what is unique? What is its chemical composition and physical properties? These questions interest many.
What is the name of the air shell of the Earth?
It is known that life on Earth is possible largely due to the unique composition of the air. And the gas shell is called the atmosphere. This part of the biosphere completely surrounds the planet and is held around a celestial body due to gravity.
Naturally, this shell has certain chemical and physical properties. As for the borders, it is impossible to clearly draw them. Closer to the earth's surface, the atmosphere contacts the lithosphere and hydrosphere. But to determine where the gas shell ends and outer space begins is extremely difficult. Today, it is customary to draw the border at an altitude of 100 km, where the so-called Karman line is located - in this area aeronautics is no longer possible.
Atmosphere - the air shell of the Earth, the value of which is difficult to overestimate. After all, do not forget that almost all celestial bodies are under the influence of ionizing and ultraviolet radiation, which are harmful to living organisms. It is in the gas shell that these rays are neutralized.
Theory of Atmosphere
In fact, many people wonder how the Earth’s air envelope formed. The answer to this question can hardly be exact, since today there are several different theories about the origin of the atmosphere.
According to the most common hypothesis, the primary atmosphere was formed four billion years ago from light gases, namely helium and hydrogen, which were captured from interplanetary space. Due to the high volcanic activity, a secondary gas shell was subsequently created, which was saturated with carbon dioxide, water vapor, and ammonia.
The tertiary atmosphere was formed due to many processes - chemical reactions (for example, lightning discharges), ultraviolet radiation, the leakage of helium and hydrogen back into interplanetary space.
Chemical composition of the atmosphere
Now that it has become clear what the name of the air shell of the Earth is, it is worth considering its chemical composition, which is considered unique. It should immediately be noted that only the lower atmosphere is saturated with various gases. In particular, nitrogen prevails in the air we breathe (78.08%). The oxygen level is 20.95%. These are two main gases.
In addition, the Earth’s air envelope includes other components — such as carbon dioxide, hydrogen, argon, helium, xenon, methane, sulfur and nitrogen oxides, ozone, and ammonia.
The structure of the air shell of the Earth
The atmosphere is usually divided into several main layers, each of which has different physical and chemical characteristics.
- The troposphere is the closest layer to the surface of the earth. It is here that 80% of all air is concentrated. And it is here that human activity is possible. By the way, almost all atmospheric water (90%) is concentrated in this layer. Clouds and precipitation form here. The troposphere extends 18 km from the surface of the earth. As you go up, the temperature drops here.
- The Stratosphere (12-50 km) is a layer that is considered the most calm part of the atmosphere. It is here that the ozone protective layer is located.
- The thermosphere is part of the atmosphere, the upper boundary of which is approximately 700-800 km. Here, the temperature begins to rise sharply with an increase, and in some areas it is about 1200 degrees Celsius. Within the boundaries of this layer is the so-called ionosphere, where air is strongly ionized under the influence of solar radiation.
- The exosphere is a scattering zone, which at an altitude of 3000 km passes into outer space. The air here is saturated with light gases, in particular hydrogen and helium.
Basic physical characteristics of the atmosphere
Of course, the physical properties of air are extremely important. For example, knowing them, one can determine how the atmosphere affects a human or any other living organism. In addition, the measurement of physical parameters is simply necessary to determine the optimal characteristics of aircraft, aircraft, etc. In particular, the following physical indicators are taken into account:
- Air temperature is measured by the following formula: t1 = t - 6.5H (here t is the air temperature at the earth's surface, and N is the height).
- Air density is the mass of air per cubic meter.
- Pressure that can be measured in both Pascals and atmospheres.
- Humidity shows the amount of water in a unit of air. It should be noted that zero humidity is possible only in laboratory conditions. The higher this indicator, the lower the air density, and vice versa.
By the way, the science that answers the questions about the name of the air shell of the Earth, what are its properties and characteristics, is meteorology. Scientists not only study the atmosphere, but also monitor its constant changes that affect the weather and climate.
Atmosphere and its meaning
The importance of the Earth’s gas envelope is very difficult to overestimate. After all, just a few minutes without air lead to loss of consciousness, hypoxia and irreversible brain damage. Only thanks to the amazing composition of the atmosphere, living organisms can receive the oxygen they need.
In addition, the air shell protects the surface of the planet from harmful cosmic radiation. At the same time, a sufficient amount of ultraviolet rays pass through the atmosphere, which warm the Earth. Scientists say that a decrease in ultraviolet radiation will lead to a decrease in overall temperature and freezing. In addition, under the influence of sunlight (in a reasonable amount), vitamin D is formed in human skin tissues.
The ozone layer and its significance
In the stratosphere, at an altitude of 12-50 km from the surface of the earth, is the ozone layer. This part of the atmosphere was discovered in 1912 by French scientists S. Fabry and A. Buisson.
Ozone is a colorless gas with a pungent characteristic odor. It consists of three oxygen atoms. It is this part of the gas shell that protects the earth's surface from dangerous cosmic radiation.
Unfortunately, due to technical and industrial progress, the amount of harmful substances that gradually destroy the ozone layer has increased in the Earth’s air envelope. So-called ozone holes are an extremely dangerous problem.
Air pollution: the greenhouse effect and acid rain
Unfortunately, constant air pollution, which is mainly associated with developed industry, leads to a lot of deterioration. Such dangerous changes include the so-called greenhouse effect. The fact is that earthly bodies emit mainly infrared waves - they can not always penetrate the atmosphere. An increase in the concentration of greenhouse gases that absorb infrared radiation (water vapor, carbon dioxide) leads to an increase in the total temperature in the lower atmosphere, which, accordingly, affects the climate.
Acid rain is another result of industrial pollution of the Earth’s air envelope. Sulfur and nitrogen oxides, which are emitted into the air by thermal power plants, automobiles, metallurgical plants and some other enterprises, can react with atmospheric water vapor - acids form here under the influence of solar radiation, which precipitate together with other precipitation.