What is it : the air ?
air - the most important substance, without access to which man will not survive a few minutes.We all understand how important the air for us, but do we know what it is?
Unfortunately, knowledge of most of us in this matter is very limited.Let's correct the situation.
Strictly speaking, the air - it is a natural mixture of gases that forms the Earth's atmosphere.The main component of the air determines its critical role in the vital activity of living organisms, is oxygen.Oxygen is used in oxidative processes, which resulted in the allocated energy necessary for life.
chemical composition of air
Scottish scientist Joseph Black in 1754 through a series of experiments demonstrated that the air - is not a homogeneous substance, but a mixture of gases.The chemical composition of the air has been identified by the French scientist Antoine Lavoisier.So what makes up our earthly shell:
- nitrogen - 78%;
- oxygen - 21%;
- other gases (carbon dioxide, argon, neon, methane, helium, krypton, hydrogen, xenon) - 1%.
Incidentally, the air was not always such - 4 billion years ago, at the dawn of our planet, the air, mainly, is carbon dioxide.Needless to say, that life developed just could not under these conditions.Carbon dioxide gradually entered into the various reaction (dissolved in water, react with rocks) and its content in the air decreased.
When there were green plants that are known to actively absorb carbon dioxide and use it in the process of life, its content in the atmosphere began to decline more quickly, until finally, not yet formed the final composition.
In fairness it should be noted that this is the final composition of 78% / 21% / 1% varies depending on the location: in the woods there is a minimal part of the impurities, and in large cities, on the other hand, the maximum.Furthermore, light in different parts of the content of a particular gas may vary within 3% for each.
The main physical properties include air its temperature, humidity and atmospheric pressure.Each of these properties in a special way affects the state of the environment and humans.
air temperature determines the thermal state of the environment, ie heat.Elevated temperatures will adversely affect heat transfer.
At elevated temperatures (over 35 degrees Celsius), the body gets rid of excess heat mainly by sweating.At the output from the body then the salt and water-soluble vitamins, which leads to a weight of negative effects, in particular - to increase the viscosity of the blood, heart and difficulties etc.Excessive overheating of the body can lead to heat stroke.
At low temperatures, the body experiences a deficiency heat.Total cooling is accompanied by a weakening of the muscular activity promotes local colds.
Humidity characterizes the content of water vapor in the air.Excessively dry air adversely affects the mucous membranes of the upper respiratory tract, causing inflammation and cracks.
Changing the atmospheric pressure is particularly acute in middle age, and sudden pressure changes cause negative effects in the young organism.
Low atmospheric pressure leads to hypoxia (lack of oxygen), which, in turn, provokes headaches, disturbances of coordination, drowsiness, etc.
Among the negative effects of increased atmospheric pressure - increased heart rate, respiration, and increase in the maximum lowering the minimum blood pressure, etc.
As you can see, the air, and then what he is - a dry or wet, hot or cold - plays a crucial role.Thus, the air is not only necessary for the vital activity of living organisms, it also determines the quality of this very life.
More about the most important for us to read the substance in the articles:
- Air Properties |What is the air
- How to moisten the air