What is the mass of air? Ancient scientists did not know the answer to this question. During the infancy of science, many believed that air had no mass. In the ancient world and even in the early Middle Ages, numerous misconceptions were widespread related to the lack of knowledge and the lack of accurate instruments. Not only such a physical quantity as the mass of air has made it to the list of funny misconceptions.
Medieval scientists (it would be more correct to call them inquisitive monks), not being able to measure non-obvious quantities, quite seriously believed that light propagates in space infinitely fast. However, this is not surprising. Science then interested very, very few. Much more people at that time gathered theological discussions on the topic "how many angels will fit on the point of a needle."
But as time went on, knowledge about the world became more voluminous. Scientists already knew that everything in the world has weight, but they could not yet calculate what the mass of air is. And finally, in the eighteenth centurymanaged to calculate the density of air, and with it the mass of the entire earth's atmosphere. The total air mass of our planet turned out to be equal to a number with seventeen zeros - 53x1017 kilogram. True, this figure also includes the mass of water vapor, which is also part of the atmosphere.
Today it is generally accepted that the thickness of the Earth's atmosphere is about one hundred and twenty kilometers, and the air is unevenly distributed in it. The lower layers are denser, but gradually the number of gas molecules that make up the atmosphere per unit volume decreases and disappears.
The specific gravity of air (density) at the surface of the Earth under normal conditions is approximately one thousand three hundred grams per cubic meter. At an altitude of twelve kilometers, the air density decreases by more than four times and already has a value of three hundred and nineteen grams per cubic meter.
The atmosphere is made up of several gases. Ninety-eight to ninety-nine percent is nitrogen and oxygen. In small quantities there are others - carbon dioxide, argon, neon, helium, methane, carbon. The first to determine that air is not a gas, but a mixture, was the Scottish scientist Joseph Black in the mid-eighteenth century.
At altitudes over two thousand meters, both the pressure of the atmosphere and the percentage of oxygen in it decrease. This circumstance became the cause of the so-called " altitude sickness". Doctors distinguish several stages of this disease. In the worst case, it is hemoptysis, pulmonary edema and death.
The internal pressure of the human body at high altitude becomes much greater than atmospheric pressure, and the circulatory system begins to fail. Capillaries break first.
It has been established that the height limit that people can withstand without an oxygen device is eight thousand meters. Yes, and only a well-trained person can reach eight thousand. Long-term living in highlands adversely affects he alth. Doctors observed a group of Peruvians who lived for generations at an altitude of 3500-4000 meters above sea level. They noted a decrease in mental and physical performance, there are changes in the central nervous system. That is, the highlands are not suitable for human life. And a person can not adapt to life there. And is it necessary?
