That part of the atmosphere that is adjacent to the Earth andwhich the person breathes accordingly, is called the troposphere. The troposphere has a height of nine to eleven kilometers and is a mechanical mixture of various gases.
The composition of the air does not possess constancy.Depending on the geographical location, location, weather conditions, population density, the air can have different composition and different properties. The air can be gassed or discharged, fresh or heavy - all this means that it contains certain impurities.
However, it is considered to be the following standard composition of air in percent:
- nitrogen - 78.9 percent;
- oxygen - 20.95 percent;
- carbon dioxide - 0.3 percent.
In addition, in the atmosphere there are other gases (helium, argon, neon, xenon, krypton, hydrogen, radon, ozone), as well as nitrous oxide and water vapor. Their sum is a little less than one percent.
Also worth pointing to the presence in the airsome permanent impurities of natural origin, in particular, some gaseous products, which are formed as a result of both biological and chemical processes. Ammonia deserves a special mention among them (the air composition far from populated areas includes about three to five thousandths of a milligram per cubic meter), methane (its level is on average two to ten thousandths of a milligram per cubic meter), nitrogen oxides (in the atmosphere their concentration reaches approximately fifteen ten-thousandths of a milligram per cubic meter), hydrogen sulfide and other gaseous products.
In addition to vapor and gas impurities,The chemical composition of air usually includes dust of cosmic origin, which falls on the Earth's surface in the amount of seven hundred thousand tons per square kilometer during the year, as well as dust particles that come during volcanic eruptions.
However, it changes the most (and notthe best side is the composition of the air and pollutes the troposphere so-called terrestrial (plant, soil) dust and smoke of forest fires. Especially a lot of such dust in the continental air masses, originating in the deserts of Central Asia and Africa. That is why it can be said with confidence that there is simply no perfectly clean air environment, and it is a concept that exists only theoretically.
The composition of the air has a property constantlychange, and its natural changes usually play a fairly small role, especially in comparison with the possible consequences of its artificial violations. Such violations are mainly associated with the production activities of mankind, the use of devices for consumer services, as well as vehicles. These violations can lead, among other things, to denaturation of air, that is, to pronounced differences in its composition and properties from the corresponding indicators of the atmosphere.
These and many other types of humanactivities led to the fact that the main part of the air began to undergo slow and insignificant, but nonetheless absolutely irreversible changes. For example, scientists have calculated that over the past fifty years, mankind has used about as much oxygen as the previous million years, and as a percentage - two tenths of a percent of its total stock in the atmosphere. This increases the emission of carbon dioxide into the air shell of the Earth. This latest release has reached nearly four hundred billion tons over the past hundred years.
Thus, the composition of the air is changing for the worse, and it is difficult to guess what it will become in a few decades.
