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4.3. Chemical composition of the atmosphere

Chemical composition of the atmosphere

The atmosphere is made up of air  (a homogeneous mixture of gases in different proportions), and atmospheric dust, small particles that float in the air (pollen, fine sand, volcanic ash, etc.).

The composition of the air is:

Composición de la atmósfera terrestre (tomada en diciembre de 1987). El gráfico de la parte inferior indica los gases menos comunes que componen el 0,038 % de la atmósfera. Los valores están redondeados para la ilustración.

By Nicolás Lichtmaier [Public domain], via Wikimedia Commons

Air density decreases at high altitudes. Most of the air mass is in the low-lying areas, attracted by the force of Earth's gravity. On the other hand, in the higher areas, the air is thinner and lighter, with less density.

Air density and atmospheric pressure decrease height.

Curiosity: Altitude sickness

Altitude sickness is caused by the non-adaptation of the body to the lack of oxygen with altitude. It usually occurs between 2400 meters and 8000 meters of altitude. It occurs more frequently among those under 50 years of age, and among those who usually live at less than 900 meters of altitude.

It can cause serious problems if the altitude is very high and you have climbed there at a high speed. If you descend to lower levels, the symptoms of altitude sickness disappear.

As atmospheric pressure decreases with altitude, there is less oxygen available to the body. Lhe pulmonary alveoli cannot oxygenate the same amount of blood as if it were at higher pressure. The body slowly adapts to these circumstances by producing more red blood cells so that they can carry the little oxygen that comes from the air.

Some athletes train at high altitude, especially if their competition is going to be in high areas, to produce a greater number of red blood cells. Other cheating athletes dope themselves by injecting the hormone erythropoietin (EPO) to achieve these effects.

Musical minutes

What do you think about the composition of the air that Mecano tells us in his song "Air"?