Air

Air allegoryMarten de Vos, Museo del Prado.

Air is the name given to the dissolution of gases that make up the Earth's atmosphere, which remain within the planet Earth due to the force of gravity. Air is essential for life on the planet and transparent to the naked eye. Rayleigh scattering of visible light from the Sun (white, because waves of all wavelengths overlap) at blue wavelengths (10,000 Å) gives the atmosphere a bluish color.

It is a mixture of gases in slightly variable proportions, composed of 21% oxygen, 78% nitrogen, 0.89% noble gases, 0.1% water and small amounts of other gases. Air also contains a variable amount of water vapor, on average about 1% at sea level and 0.4% across the entire atmosphere.

Air properties

Composition of the Earth's atmosphere (taken in December 1987). The graph at the bottom indicates the less common gases that make up 0.038 % of the atmosphere. The values are rounded for illustration.

Based on altitude, temperature, and air composition, Earth's atmosphere is divided into five layers: exosphere, troposphere, stratosphere, mesosphere, and thermosphere. At higher altitudes the pressure and weight of the air decrease.

The most important portions for air pollution analysis are the two layers near Earth: the troposphere and the stratosphere. The air in the troposphere is involved in respiration. By volume it is composed of approximately 78.08% Nitrogen (N₂), 20.94% Oxygen (O₂), 0.93% Argon (Ar), 0.035% of carbon dioxide (CO₂) and 0.003% of inert gases, such as neon.

In this layer, 7 km high at the poles and 16 km high in the tropics, are the clouds and almost all the water vapor. It generates all the atmospheric phenomena that cause the climate. Higher up, approximately 25 km high, in the stratosphere, is the ozone layer, which protects the Earth from ultraviolet (UV) rays.

In relation to this it is worth remembering that, in general terms, a pollutant is a substance that is "out of place", and that a good example of this could be the case of ozone (O₃).

When this gas is found in the air that is breathed, that is, below the usual 25 kilometers of altitude, it is polluting and constitutes a powerful antiseptic that has a harmful effect on health, for which reason in these circumstances it is known as tropospheric ozone or bad ozone.

However, the same gas, when it is in the stratosphere, forms the layer that protects all living beings (life) on Earth from the ultraviolet rays of the Sun, for which reason it is identified as ozone good.

Mythology

The Romans worshiped the air, either under the name of Jupiter, whom they took for the purest air or for the ether, or under the name of Juno, which they considered the densest air that surrounds us, or with the of Minerva in addition to other times that they used to make a particular deity out of the air to whom they gave the moon as a wife and the dew as a daughter.

In the Ephigeny of Euripides Menelaus takes the air as witness to the words of Agamemnon, and Aristophanes cites this passage as a crime committed by Euripides. He was supposed to be educated by the seasons to indicate the different air temperatures at these four times of the year. The moderns have represented the air under the figure of a woman seated on a cloud. Her scattered hair and fluttering garments herald that she is in the empire of the winds. With one hand she caresses a peacock, a bird sacred to Juno, and with the other she holds a chameleon, because some suppose that she derives all her subsistence from this element. Flying animals of all kinds fly around this matron, from the eagle to the mosquito.

He is also given a garment made from the remains of an eagle and is often symbolized by Iris with her veil, Juno with her peacock, or Zephyr with his little wings. The statue representing air in the Paris mint is characterized by a pelican placed at its feet, a bird that is said to have been born from this fluid and that poets and artists have adopted as their allegorical emblem. The figure directs its eyes towards the sky and has its left foot raised in an attitude of throwing itself into the region of the atmosphere. In a painting by Brueghel de Velours in the Milan museum, the air is filled with a thousand birds, butterflies, beetles, insects, etc. whom a child observes with his telescope until light clouds hide them from his view.

In the different Mediterranean cultures (such as the Greek or the Mesopotamian) it was believed that the gods breathed life by introducing air (spirit / soul) to living beings, such as man. In the Tanaj, for example, it is related how Yahweh introduces this life to a clay sculpture made by him in his & # 34; image and likeness & # 34; (Genesis 2:7).

– The word soul comes from the Latin anima, which in turn comes from the Greek ανεμος (anemos), whose root is the Indo-European anu and whose meaning is “wind ”.

From the same root comes the word “animal” and also from the same root comes the verb “to animate” (animare, to give life).

– The word spirit comes from the Latin spiritus and this from the verb spirare (to blow).

– In Hebrew the word soul is נפש, néfesch, which means “throat” and comes from the root “to breathe” (Ras Shamra, UT 129, 137).

– In Hebrew the word spirit is רוח, ruach, which means “wind”.

Physical properties

Note: Values at 1 atm (1.01325×10⁵ Pa).
Reference: www.efunda.com

Atmospheric air composition

Air is composed mainly of nitrogen, oxygen, and argon. The rest of the components, among which are greenhouse gases, are water vapor, carbon dioxide, methane, nitrous oxide, ozone, among others. In small quantities, other substances may exist: dust, pollen, spores and volcanic ash. Gases discharged into the atmosphere as pollutants are also detectable, such as chlorine and its compounds, fluorine, mercury and sulfur compounds.