That part of the atmosphere, which is adjacent to the world and that people breathe, respectively, called the troposphere.The troposphere is the height from nine to eleven kilometers and is a mechanical mixture of different gases.
composition of the air does not have the consistency.Depending on the geographic location, terrain, weather conditions, population density, the air can have a different composition and different properties.The air may be discharged or gassy, or fresh heavy - all this means that there are certain impurities.
however, considered to be the next standard composition of the air in percent:
- nitrogen - 78.9 percent;
- oxygen - 20.95 per cent;
- carbon dioxide - 0.3 percent.
addition, there are other atmospheric gases (helium, argon, neon, xenon, krypton, hydrogen, radon, ozone), and nitrous oxide, and water vapor.The amount of a little less than one percent.
also worth pointing out the presence of air in some unavoidable impurity of natural origin, in particular, some gaseous products, which are formed by both biological and chemical processes.Special mention among them deserves ammonia (composition of the air away from the populated areas includes about three to five thousandths of a milligram per cubic meter), methane (its level is equal to the average of the two ten thousandth of a milligram per cubic meter), nitrogen oxides (atmospheric concentration reachesapproximately ten-fifteen milligrams per cubic meter), hydrogen sulfide, and other gaseous products.
addition to vapor and gaseous impurities, chemical composition of air usually involves the origin of cosmic dust that falls on the Earth's surface in the amount of seven hundred thousandth tons per square kilometer within a year, as well as dust particles, which arrive at the volcanic eruptions.
However, the greatest change (and not for the better) the composition of the air and pollutes the troposphere so-called terrestrial (vegetation, soil) dust and smoke of forest fires.Especially a lot of dust in the continental air masses originating in the deserts of Central Asia and Africa.That is why it is safe to say that a perfectly clean air environment simply does not exist, and it is a concept that exists only in theory.
composition of the air tends to change constantly, and its natural variations is usually played fairly small role, especially in comparison with the possible consequences of its artificial disturbances.Such violations are mainly related to the production of human activity, the use of devices for consumer services, as well as vehicles.These disorders can lead including a denaturation of air, that is, to distinguish it clearly defined the composition and properties of relevant indicators of the atmosphere.
These and many other human activities have led to the fact that the main part of the air have begun to slow and insignificant, but nevertheless absolutely irreversible changes.For example, scientists estimate that over the past fifty years, humanity has been used about the same amount of oxygen as for the previous million years, and as a percentage - two per cent of its total stock in the atmosphere.Thus correspondingly increased carbon dioxide emissions into the air cover of the Earth.This release of the latest figures reached almost four hundred billion tons in the last hundred years.
Thus, the composition of the air is changing for the worse, and is difficult to imagine how it will be in a few decades.
