Air is a more or less homogeneous mass of gases contained in the Earth’s atmosphere by the thrust of the gravity force of the planet.
The air is a transparent substance (in most cases), of varied and permeable constitution, not very dense, that opposes relatively little resistance to the bodies that move through it.
Air is vital for life on the planet as we know it, because it contains and moves from one place to another the gases necessary for respiration and photosynthesis, as well as being the channel for the transfer of water vapor, necessary in the fulfillment of the vital hydrological cycle.
The air is made up of different chemical substances in a gaseous state and in slightly variable proportions according to the place of the planet. In broad strokes the proportions are:
1% of other substances
These “other substances” are usually: ozone, carbon dioxide, hydrogen and other noble gases such as neon, krypton, xenon or argon. It also contains, in smaller quantities, methane gas, carbon monoxide and Ammonia, substances whose growth in the atmosphere has been linked to the margins of air pollution resulting from human activities.
2. Physical properties
The physical properties of air as a whole are typical of the gaseous state of matter, namely:
It does not have a defined volume, but fills the empty spaces uniformly.
It is sensitive to temperature: it expands and rises in the presence of heat, or it contracts and falls on cooling. This is due to the rhythm of activity that the heat imposes on its particles.
It has low density, so it is penetrable with little resistance.
It exerts pressure on objects. The pressure on the earth’s surface is called atmospheric pressure.
Modifies its properties in the heights: the higher the temperature, the lower the density, but the higher the atmospheric pressure.
3. The winds
Broadly speaking, the winds are due to the phenomena of expansion and movement of air in the atmosphere: a mass of air moves horizontally from a point A to a point B, thus compensating for pressure differences that exist between them.
Such variation is possible thanks to the heating of air masses, product of solar radiation or other processes, and that hot air rises and pushes upwards, letting its place be occupied by a new equivalent mass of colder air, that will heat up in turn and so on.
4. Climate and thermal sensation
The different phenomena that give rise to the different climates that exist, take place in the atmosphere and directly affect the composition of the air: its tendency to cool, its mobility, its pressure and the humidity levels in the air.
Hence, for example, that there is a discrepancy between the recorded temperature and the thermal sensation, since the amount of wind and atmospheric humidity directly influence the amount of perceived temperature.
5. The atmosphere
The mass of air that surrounds the Earth, in its different levels or layers, is called atmosphere. In it the different gases that make up the air are kept together, but in different proportions according to the height reached, since the largest volume of gases is concentrated, by gravitational action, in the initial 11km of the atmosphere, that is, the that are closer to the ground.
The atmosphere extends up to 10,000 km away, but as the air moves away from the ground, it loses density, temperature and concentration of vital gases such as oxygen. It is there that when climbing particularly steep summits, travelers require special support or at least a training in hypoxia, because breathing will be much more difficult at the top.
6. The ozone layer
At the outer levels of the atmosphere, the air reaches particular properties and allows the abundant existence of ozone, a variant of oxygen (three oxygen atoms together constitute an ozone molecule) that retains its stability only under special conditions of pressure and temperature.
In this way, a layer of said gas is formed that is extremely beneficial for life on the planet, and is called the ozone layer. This layer has the property of filtering the sun’s ultraviolet radiation and preventing its impact on the ground from being harmful.
One of the greatest consequences of the pollution of the terrestrial air has been, precisely, the reduction of this important layer.
7. Natural disasters
Hurricanes and tornadoes are some of the natural disasters that can be generated from specific air conditions in the atmosphere, and that contain a high destructive potential that often translates into a high cost of human lives. Each one has different characteristics and origins.
Hurricanes have their origin in hot air masses of the tropics and consist of a closed circuit of humid air flow in condensation, revolving around a warm core of low pressure. This causes intense rains and winds of great importance, and depending on how much they can be classified in tropical depression, tropical storm, hurricane, typhoon or cyclone.
Tornadoes are usually brief (a few seconds or an hour) but intense, and consist of a column of air that rotates on its axis at very high speeds, product of confluences of air masses of opposite temperatures. Thus a rotating column is formed in contact with the ground and usually under a cumuliform cloud, which gives it its distinguishable but not always visible funnel appearance.
8. Air pollution
Just like water or any environment, the air suffers the effects of the insertion of foreign substances to its natural composition, being able to lose many of its intrinsic qualities or even spreading substances harmful to life.
This contamination can be natural, being the product of geographic accidents or unpredictable events such as the explosion of volcanoes, the impact of meteorites or certain types of substance emitted by animals or large areas of vegetation.
On the other hand, artificial pollution has to do with man’s activities, preferably those of industrial type that release toxic substances into the atmosphere, such as carbon monoxide, ozone, sulfur dioxide or suspended lead particles. Many of these compounds do not even exist in the natural state, and their effects can be extremely damaging to the terrestrial ecosystem.
9. Hazards of air pollution
There are cities such as Mexico City or Santiago de Chile, where levels of air pollution generate ecological warnings among its population, forced to take measures against the poor quality of the air they breathe, loaded with toxic particles released by automotive traffic and industry. energetic, accumulated on the city in the days of little wind.
Similarly, phenomena such as acid rain or the much debated greenhouse effect have been recorded in other regions of the world, whose explanation is that the polluting gas emissions would be rapidly destroying the ozone layer, allowing solar radiation to enter the planet directly.
This would cause damage to living beings (skin cancer, burns, etc.) and increase the global temperature, causing the melting of the poles and the rise of ocean levels, which in turn would wipe out entire cities.
10. The air in culture
Since time immemorial has been air as an essential part of life. According to the Greek philosopher Anaximenes, air was the essential substrate of all things, while for later philosophers it was one of the four basic elements of matter, together with fire, water and earth. This theory, which survived until after the Middle Ages, was known as the theory of the four humors.
The anemoi, Greek gods of the winds, had a name depending on where they were blowing, and therefore a different story; but they alternated between charitable and delicate deities, of ethereal and frank spirit, and others of impetuous and terrible spirit, carriers of storms and destroyers of crops.
Similarly, sites of intense windy frequency, such as Mont Ventoux de Petrarca, in Provence, Italy, always enjoyed a particular consideration in the culture.
Currently, global warming caused by the greenhouse effect occupies a huge space of our thinking, whether studying ways to combat or retard it, or even debating its veracity through scientific perspectives.