As we have already seen, the air layer that comes into contact with the Earth's surface is called troposphere which has a thickness between 8 and 16 km.
Due to natural factors such as volcanic eruptions, relief, vegetation, oceans, rivers and human factors such as industries, cities, agriculture and man himself, the air suffers up to a height of 3 km. , influences on its basic characteristics.
All the layers that make up our atmosphere have their own characteristics that are important for protecting the earth. Above 25 km, for example, there is an ozone concentration (O3) which acts as a filter, preventing the passage of some harmful radiation to life. Ultraviolet rays that could kill life in large quantities are largely filtered by it. ozone layer.
The portion of ultraviolet rays that reach the earth is beneficial for both the elimination of bacteria and the prevention of disease. Our atmospheric air has not always been the way it is today, it has varied over time. Probably the air that enveloped the earth was primarily formed of methane gas (CH4), ammonia (NH3), water vapor and hydrogen (H2). With the emergence of living beings, especially vegetables, the atmosphere was changed.
Currently, as we already know, air is made up of approximately 78% nitrogen (N2), 21% oxygen, 0.03% carbon dioxide (CO2) as well as noble gases and water vapor. This composition presents variations according to the altitude.
Factors that cause changes in air
The change in the chemical constitution of air over time indicates that air continues to change as man promotes changes in the environment. So far this gaseous and transparent mixture has allowed the sun's filtration and heat retention, which are fundamental to life. It can be said, however, that life on earth depends on the conservation and even improvement of present air characteristics.
The main factors that have contributed to cause changes in air are:
- Air pollution by industries, which in some regions has already caused a decrease in air transparency;
- O increased number of supersonic aircraft which, because they fly at high altitudes, alter the ozone layer;
- the deforestationwhich decreasing green areas cause a decrease in oxygen production;
- at experimental atomic explosions, which release large amounts of gas, solid waste and energy into the atmosphere;
- the automobiles and industries, which consume oxygen and release large amounts of carbon monoxide (CO) and carbon dioxide (CO2).
All these factors, when associated, put at risk the total equilibrium of the planet and may cause, among other phenomena, the so-called greenhouse effect, which can cause a serious rise in the temperature of the earth, which will lead to serious consequences.