The reason for the occurrence of ozone holes in the atmosphere is an increase. Will humanity cope with the upcoming challenges? Encounter with ozone in everyday life
About forty years ago, it was first discovered that the ozone layer in earth's atmosphere began to dwindle. The first to notice this were British scientists who worked at a research base in Antarctica. They found that over the Halley Bay station, the thickness of the ozone had almost halved! While possible reasons of this phenomenon had not yet been studied, so all that remained for scientists to do was to observe the development of the situation. And the results did not please them at all - the ozone holes not only did not close, but even spread far beyond South Pole. So there was information about a new global catastrophe.
What exactly are ozone holes?
Ozone is a gas that is produced from oxygen by ultraviolet radiation from the sun. It, in turn, prevents the passage of this radiation, the effect of which is detrimental to all living organisms. A layer of this gas is located at an altitude of about twenty kilometers above the surface and protects the planet from negative impact solar energy. Ozone holes are places where the thickness of the gas decreases for some reason. At this stage, it is still enough to delay the ultraviolet, but if humanity does nothing to change the situation, after a while the depletion of the ozone layer will lead to the fact that harmful radiation can freely penetrate the atmosphere, and then the existence of life on Earth will simply become impossible.
Why do ozone holes appear?
Space exploration
And yet, despite the wide variety of possible versions, the most probable of them remains anthropogenic. Indeed, in the middle of the last century, there were numerous launches space rockets, each of which, taking off, left a "hole" in the atmosphere, breaking through the ozone layer. In just thirty years of space exploration, 30% of the protective barrier of the Earth, which was formed over four billion years, was destroyed!
Freon
Freon is a destructive substance for ozone, which is widely used both in everyday life and in industry. It was contained in almost all gas cartridges of the last century: in hair sprays, perfumes, deodorants, fire extinguishers. It was even in refrigerators and air conditioners! It is not surprising that every day more and more new ozone holes appeared, and the protective layer became thinner and thinner.
Solutions
To date, the problem remains acute and relevant. Numerous agreements have been adopted under which substances harmful to the ozone layer are prohibited from being used in production and industry. But this is not enough, because the question is not only to stop the destruction of ozone, but also to restore it. And this problem has not been solved yet.
These and other recent scientific findings reinforced the conclusion of previous assessments that the body of scientific evidence suggests that the observed loss of ozone at mid and high latitudes is mainly due to anthropogenic chlorine- and bromine-containing compounds.
Original text (English)
These and other recent scientific findings strengthen the conclusion of the previous assessment that the weight of scientific evidence suggests that the observed middle- and high-latitude ozone losses are largely due to anthropogenic chlorine and bromine compounds
According to another hypothesis, the process of formation of "ozone holes" can be largely natural and is not associated exclusively with harmful effects human civilization.
To determine the boundaries of the ozone hole, a minimum level of ozone in the atmosphere of 220 Dobson units was chosen.
The area of the ozone hole over Antarctica averaged 22.8 million square kilometers in 2018 (in 2010-2017, the average annual values ranged from 17.4 to 25.6 million square kilometers, in 2000-2009 - from 12.0 to 26 .6 million square kilometers, in 1990-1999 - from 18.8 to 25.9 million square kilometers).
Story [ | ]
An ozone hole with a diameter of over 1000 km was first discovered in 1985 in the Southern Hemisphere, over Antarctica, by a group of British scientists: (English), (English), (English), who published a corresponding article in the journal Nature. Every August it appeared, and in December - January it ceased to exist. Numerous mini-ozone holes exist over the Northern Hemisphere in the Arctic in autumn and winter. The area of such a hole does not exceed 2 million km², its lifetime is up to 7 days.
Mechanism of education[ | ]
As a result of the absence solar radiation, no ozone is formed during polar nights. No ultraviolet - no ozone. Having a large mass, ozone molecules descend to the Earth's surface and are destroyed, as they are unstable at normal pressure.
Rowland and Molina suggested that chlorine atoms could cause the destruction of large amounts of ozone in the stratosphere. Their findings were based on similar work by Paul Joseph Crutzen and Harold Johnstone, who showed that nitric oxide (II) (NO) can accelerate ozone depletion.
A combination of factors leads to a decrease in the concentration of ozone in the atmosphere, the main of which is the death of ozone molecules in reactions with various substances of anthropogenic and natural origin, the absence of solar radiation during the polar winter, a particularly stable polar vortex that prevents the penetration of ozone from subpolar latitudes, and the formation of polar stratospheric clouds (PSC), the surface of whose particles catalyze ozone decay reactions. These factors are especially characteristic of the Antarctic, in the Arctic the polar vortex is much weaker due to the lack of a continental surface, the temperature is several degrees higher than in the Antarctic, and PSOs are less common, and they also tend to break up in early autumn. Being reactive, ozone molecules can react with many inorganic and organic compounds. The main substances contributing to the destruction of ozone molecules are simple substances (hydrogen, oxygen atoms, chlorine, bromine), inorganic (hydrogen chloride, nitrogen monoxide) and organic compounds (methane, fluorochlorine and fluorobromofreons, which emit chlorine and bromine atoms). Unlike, for example, hydrofluorofreons, which decompose to fluorine atoms, which, in turn, quickly react with water, forming stable hydrogen fluoride. Thus, fluorine does not participate in ozone decay reactions. Iodine also does not deplete stratospheric ozone, since iodine-containing organic matter almost completely consumed in the troposphere. The main reactions that contribute to the destruction of ozone are given in the article about the ozone layer.
Effects [ | ]
The weakening of the ozone layer increases the flow of ultraviolet solar radiation, penetrating into ocean waters, which leads to an increase in mortality among marine animals and plants.
Restoration of the ozone layer[ | ]
Although mankind has taken measures to limit emissions of chlorine- and bromine-containing freons by switching to other substances, such as fluorine-containing freons, the process of restoring the ozone layer will take several decades. First of all, this is due to the huge volume of freons already accumulated in the atmosphere, which have a lifetime of tens and even hundreds of years. Therefore, the tightening of the ozone hole should not be expected before 2048. According to Professor Susan Solomon, from 2000 to 2015 the ozone hole over Antarctica has decreased by about the area of India. According to NASA, in 2000 the average annual area of the ozone hole over Antarctica was 24.8 million square kilometers, in 2015 - 25.6 million square kilometers.
Misconceptions about the ozone hole[ | ]
There are several widespread myths about the formation of ozone holes. Despite their unscientific nature, they often appear in the media [ ] - sometimes out of ignorance, sometimes supported by conspiracy theorists. Some of them are listed below.
The ozone hole over Antarctica has been around for a long time[ | ]
Systematic scientific observations of the ozone layer of Antarctica have been carried out since the 20s of the XX century, but only in the second half of the 70s was the formation of a "stable" Antarctic ozone hole discovered, and fast pace its development (increase in size and decrease in the average concentration of ozone within the boundaries of the hole) in the 80s and 90s caused panic fears that the point of no return in the degree of destructive anthropogenic impact on the ozone layer had already been passed.
Freons are the main destroyers of ozone.[ | ]
This statement is true for middle and high latitudes. In the rest, the chlorine cycle is responsible for only 15-25% of ozone loss in the stratosphere. At the same time, it should be noted that 80% of chlorine is of anthropogenic origin (for more details about the contribution of various cycles, see the article on the ozone layer). That is, human intervention greatly increases the contribution of the chlorine cycle. And if there was a tendency to increase the production of freons before the entry into force of the Montreal Protocol (10% per year), from 30 to 50% of the total ozone loss in 2050 would be due to exposure to freons. Before human intervention, the processes of ozone formation and its destruction were in equilibrium. But freons emitted by human activity have shifted this balance towards a decrease in ozone concentration. As for the polar ozone holes, the situation is completely different. The mechanism of ozone destruction is fundamentally different from higher latitudes, the key stage is the conversion of inactive forms of halogen-containing substances into oxides, which occurs on the surface of particles of polar stratospheric clouds. And as a result, almost all ozone is destroyed in reactions with halogens, chlorine is responsible for 40-50% and bromine is about 20-40%.
DuPont position[ | ]
DuPont, after the publication of data on the participation of freons in the destruction of stratospheric ozone, took this theory with hostility and spent millions of dollars on a press campaign to protect freons. The DuPont chairman wrote in a July 16, 1975 article in Chemical Week that the ozone depletion theory was science fiction, nonsense that made no sense. In addition to DuPont, a number of companies around the world have produced and continue to produce different types freon royalty-free.
Freons are too heavy to reach the stratosphere[ | ]
It is sometimes argued that since Freon molecules are much heavier than nitrogen and oxygen, they cannot reach the stratosphere in significant quantities. However, atmospheric gases are mixed completely and not stratified or sorted by weight. Estimates of the required time for diffusional separation of gases in the atmosphere require times of the order of thousands of years. Of course, this is not possible in a dynamic atmosphere. The processes of vertical mass transfer, convection and turbulence completely mix the atmosphere below the turbopause much faster. Therefore, even such heavy gases as inert or freons are evenly distributed in the atmosphere, including reaching the stratosphere. Experimental measurements of their concentrations in the atmosphere confirm this; Measurements also show that it takes about five years for gases released on the Earth's surface to reach the stratosphere, see the second graph on the right. If the gases in the atmosphere did not mix, then such heavy gases from its composition as argon and carbon dioxide would form a layer several tens of meters thick on the Earth's surface, which would make the Earth's surface uninhabitable. But it's not. Both krypton with an atomic mass of 84 and helium with an atomic mass of 4 have the same relative concentration, which is near the surface, which is up to 100 km in height. Of course, all of the above is only true for gases that are relatively stable, like freons or inert gases. Substances that enter into reactions and are also subjected to various physical influences, say, dissolve in water, have a dependence of concentration on height.
The main sources of halogens are natural, not anthropogenic[ | ]
Sources of chlorine in the stratosphere
There is an opinion that natural sources of halogens, such as volcanoes or oceans, are more significant for the process of ozone depletion than those produced by man. Without questioning the contribution natural sources in the overall balance of halogens, it should be noted that they mostly do not reach the stratosphere due to the fact that they are water-soluble (mainly chloride ions and hydrogen chloride) and are washed out of the atmosphere, falling as rain on the ground. Also, natural compounds are less stable than freons, for example, methyl chloride has an atmospheric lifetime of only about a year, compared to tens and hundreds of years for freons. Therefore, their contribution to the destruction of stratospheric ozone is rather small. Even the rare eruption of Mount Pinatubo in June 1991 caused a drop in ozone levels not due to the released halogens, but due to the formation of a large mass of sulfuric acid aerosols, the surface of which catalyzed ozone destruction reactions. Fortunately, after three years, almost the entire mass of volcanic aerosols was removed from the atmosphere. Thus, volcanic eruptions are relatively short-term factors affecting the ozone layer, unlike freons, which have lifetimes of tens and hundreds of years.
The ozone hole must be above the freon sources[ | ]
Dynamics of changes in the size of the ozone hole and ozone concentration in Antarctica by years
Many do not understand why the ozone hole is formed in the Antarctic, when the main emissions of freons occur in the Northern Hemisphere. The fact is that freons are well mixed in the troposphere and stratosphere. Due to their low reactivity, they are practically not consumed in the lower layers of the atmosphere and have a lifetime of several years or even decades. Being highly volatile molecular compounds, they reach the upper atmosphere relatively easily.
The Antarctic "ozone hole" itself does not exist year-round. It appears in late winter - early spring (August-September) and manifests itself in a noticeable decrease in the average ozone concentration within a vast geographical area. The reasons why the ozone hole forms in Antarctica are related to the features local climate. The low temperatures of the Antarctic winter lead to the formation of the polar vortex. The air inside this vortex moves mainly along closed paths around the South Pole and weakly mixes with air from other latitudes. At this time, the polar region is not illuminated by the Sun, and in the absence of ultraviolet irradiation, ozone is not formed, but accumulated before that is destroyed (both as a result of interactions with other substances and particles, and spontaneously, since ozone molecules are unstable). With the advent of the polar day, the amount of ozone gradually increases and again reaches the normal level. That is, fluctuations in ozone concentration over the Antarctic are seasonal.
But if we trace the dynamics of changes in the ozone concentration and the size of the ozone hole averaged over each year during recent decades, there is a pronounced downward trend in the mean ozone concentration over a vast geographic area.
Sources and notes[ | ]
- Scientific Assessment of Ozone Depletion: 2006(English) . Retrieved December 13, 2007. Archived from the original on February 16, 2012.
- "Knowledge is power" Science news: 27.12.99 (Russian). Retrieved July 3, 2007. Archived from the original on February 16, 2012.
The ozone layer is a wide atmospheric belt extending from 10 to 50 km above the Earth's surface. Chemically, ozone is a molecule consisting of three oxygen atoms (an oxygen molecule contains two atoms). The concentration of ozone in the atmosphere is very low, and small changes in the amount of ozone lead to large changes in the intensity of ultraviolet reaching the earth's surface. Unlike ordinary oxygen, ozone is unstable, it easily transforms into a diatomic, stable form of oxygen. Ozone is a much stronger oxidizing agent than oxygen, and this makes it capable of killing bacteria and inhibiting plant growth and development. However, due to its low normal conditions concentrations in the surface layers of air, these features of it practically do not affect the state of living systems.
Much more important is its other property, which makes this gas absolutely necessary for all life on land. This property is the ability of ozone to absorb the hard (shortwave) ultraviolet (UV) radiation from the sun. Hard UV quanta have enough energy to break some chemical bonds, so it is referred to as ionizing radiation. Like other radiation of this kind, X-ray and gamma radiation, it causes numerous disturbances in the cells of living organisms. Ozone is formed under the influence of high-energy solar radiation, which stimulates the reaction between O2 and free oxygen atoms. Under the influence of moderate radiation, it decays, absorbing the energy of this radiation. Thus, this cyclical process "eats" the dangerous ultraviolet.
Ozone molecules, like oxygen, are electrically neutral, i.e. carry no electrical charge. Therefore, the Earth's magnetic field itself does not affect the distribution of ozone in the atmosphere. The upper layer of the atmosphere - the ionosphere, almost coincides with the ozone layer.
In the polar regions where lines of force magnetic field The earth closes on its surface, the distortion of the ionosphere is very significant. The number of ions, including ionized oxygen, in the upper layers of the atmosphere of the polar zones is reduced. But main reason low ozone content in the region of the poles - low intensity of solar radiation, which falls even during the polar day at small angles to the horizon, and during the polar night is completely absent. The area of polar "holes" in the ozone layer is a reliable indicator of changes in total atmospheric ozone.
The ozone content in the atmosphere fluctuates due to many natural causes. Periodic fluctuations associated with cycles of solar activity; many components of volcanic gases are capable of destroying ozone, so an increase in volcanic activity leads to a decrease in its concentration. Thanks to the high, hurricane speeds air currents in the stratosphere, ozone-depleting substances are carried over large areas. Not only ozone depleters are transported, but also ozone itself, so ozone concentration disturbances quickly spread over large areas, and local small “holes” in the ozone shield, caused, for example, by a rocket launch, are relatively quickly drawn in. Only in polar regions the air is inactive, as a result of which the disappearance of ozone there is not compensated by its drift from other latitudes, and the polar "ozone holes", especially at the South Pole, are very stable.
Sources of destruction of the ozone layer. Among the depleters of the ozone layer are:
1) Freons.
Ozone is destroyed under the influence of chlorine compounds known as freons, which, also being destroyed under the influence of solar radiation, release chlorine, which “tear off” the “third” atom from the ozone molecules. Chlorine does not form compounds, but serves as a “rupture” catalyst. Thus, one chlorine atom is able to "destroy" a lot of ozone. It is believed that chlorine compounds are able to remain in the atmosphere from 50 to 1500 years (depending on the composition of the substance) of the Earth. Observations of the planet's ozone layer have been carried out by Antarctic expeditions since the mid-1950s.
The ozone hole over Antarctica, which increases in spring and decreases in autumn, was discovered in 1985. The discovery of meteorologists caused a chain of consequences of an economic nature. The fact is that the existence of the “hole” was blamed chemical industry, which produces substances containing freons that contribute to the destruction of ozone (from deodorants to refrigeration units).
In the question of how much a person is guilty of the formation of "ozone holes" - consensus no.
On the one hand, yes, definitely guilty. The production of ozone-depleting compounds should be minimized or, better yet, stopped altogether. That is, to abandon the whole sector of industry, with a turnover of many billions of dollars. And if you do not refuse, then transfer it to a “safe” track, which also costs money.
The point of view of skeptics: human influence on atmospheric processes, for all its destructiveness on a local level, on a planetary scale is negligible. The anti-freon campaign of the “greens” has a completely transparent economic and political background: with its help, large American corporations (DuPont, for example) stifle their foreign competitors by imposing agreements on the “protection environment"at the state level and forcibly introducing a new technological revolution, which economically weaker states are not able to withstand.
2) High-altitude aircraft.
The destruction of the ozone layer is facilitated not only by freons released into the atmosphere and entering the stratosphere. Nitrogen oxides, which are formed during nuclear explosions, are also involved in the destruction of the ozone layer. But nitrogen oxides are also formed in combustion chambers turbojet engines high-altitude aircraft. Nitrogen oxides are formed from the nitrogen and oxygen that are there. The rate of formation of nitrogen oxides is the greater, the higher the temperature, i.e., the greater the engine power.
Not only is the engine power of an aircraft important, but also the altitude at which it flies and releases ozone-destroying nitrogen oxides. The higher the oxide or nitrous oxide is formed, the more destructive it is for ozone.
The total amount of nitrogen oxide released into the atmosphere per year is estimated at 1 billion tons. About a third of this amount is emitted by aircraft above the average tropopause level (11 km). As for aircraft, the most harmful emissions are military aircraft, the number of which is in the tens of thousands. They fly mainly at the heights of the ozone layer.
3) Mineral fertilizers.
Ozone in the stratosphere can also decrease due to the fact that nitrous oxide N2O enters the stratosphere, which is formed during the denitrification of nitrogen bound by soil bacteria. The same denitrification of bound nitrogen is also carried out by microorganisms in the upper layer of the oceans and seas. The process of denitrification is directly related to the amount of bound nitrogen in the soil. Thus, one can be sure that with an increase in the amount of mineral fertilizers applied to the soil, the amount of nitrous oxide N2O formed will also increase to the same extent. Further, nitrogen oxides are formed from nitrous oxide, which lead to the destruction of stratospheric ozone.
4) Nuclear explosions.
Nuclear explosions release a lot of energy in the form of heat. The temperature equal to 60,000 K is set within a few seconds after a nuclear explosion. It's energy fireball. In a very hot atmosphere, such transformations take place chemical substances, which under normal conditions either do not occur, or proceed very slowly. As for ozone, its disappearance, the most dangerous for it are the oxides of nitrogen formed during these transformations. So, for the period from 1952 to 1971, as a result nuclear explosions about 3 million tons of nitrogen oxides were formed in the atmosphere. Further fate They are as follows: as a result of the mixing of the atmosphere, they fall to different heights, including into the atmosphere. There they enter chemical reactions with the participation of ozone, leading to its destruction. ozone hole stratosphere ecosystem
5) Fuel combustion.
Nitrous oxide is also found in flue gases from power plants. Actually, the fact that nitrogen oxide and dioxide are present in combustion products has been known for a long time. But these higher oxides do not affect ozone. They, of course, pollute the atmosphere, contribute to the formation of smog in it, but are quickly removed from the troposphere. Nitrous oxide, as already mentioned, is dangerous for ozone. At low temperatures it is formed in the following reactions:
N2 + O + M = N2O + M,
2NH3 + 2O2 =N2O = 3H2.
The scale of this phenomenon is very significant. In this way, approximately 3 million tons of nitrous oxide are formed in the atmosphere every year! This figure suggests that this source of ozone depletion is significant.
Ozone hole over Antarctica
A significant decrease in total ozone over Antarctica was first reported in 1985 by the British Antarctic Survey based on analysis of data from the Halle Bay Ozone Station (76 degrees S). Ozone depletion has also been observed by this service in the Argentine Islands (65 degrees S).
From August 28 to September 29, 1987, 13 flights of the laboratory aircraft over the Antarctic were performed. The experiment made it possible to register the origin of the ozone hole. Its dimensions were obtained. Studies have shown that the greatest decrease in the amount of ozone took place at altitudes of 14 - 19 km. Here the devices are registered the largest number aerosols (aerosol layers). It turned out that the more aerosols there are at a given altitude, the less ozone there is. Aircraft - the laboratory registered a decrease in ozone equal to 50%. Below 14 km. ozone changes were insignificant.
Already by the beginning of October 1985, the ozone hole (the minimum amount of ozone) covers pressure levels from 100 to 25 hPa, and in December the range of heights at which it is observed expands.
In many experiments, not only the amount of ozone and other small components of the atmosphere was measured, but also the temperature. The closest relationship was established between the amount of ozone in the stratosphere and the air temperature there. It turned out that the nature of the change in the amount of ozone is closely related to the thermal regime of the stratosphere over Antarctica.
The formation and development of the ozone hole in Antarctica was observed by British scientists in 1987. In the spring, the total ozone content decreased by 25%.
American researchers took measurements in Antarctica in winter and in early spring 1987 of ozone and other small constituents of the atmosphere (HCl, HF, NO, NO2, HNO3, ClONO2, N2O, CH4) using a special spectrometer. The data from these measurements made it possible to delineate an area around the South Pole in which the amount of ozone is reduced. It turned out that this region coincides almost exactly with the extreme polar stratospheric vortex. When passing through the edge of the vortex, the amount of not only ozone changed dramatically, but also other small components that affect the destruction of ozone. Within the ozone hole (or, in other words, the polar stratospheric vortex), the concentrations of HCl, NO2, and nitric acid were significantly lower than outside the vortex. This takes place because chlorins during the cold polar night destroy ozone in the corresponding reactions, acting as catalysts in them. It is in the catalytic cycle with the participation of chlorine that the main decrease in the concentration of ozone occurs (at least 80% of this decrease).
These reactions take place on the surface of the particles that make up the polar stratospheric clouds. So than more area this surface, i.e., the more particles of stratospheric clouds, and hence the clouds themselves, the faster the ozone eventually decays, which means the more efficiently the ozone hole is formed.
One of the most remarkable "green" myths is the assertion that the ozone holes above the poles of the Earth arise due to the emissions of certain substances produced by man into the atmosphere. Thousands of people still believe in it, even though any student who has not skipped chemistry and geography classes can expose this myth.
The myth that human activity leads to the growth of the so-called ozone hole is remarkable in many ways. First, it is extremely plausible, that is, based on real facts. Such as the presence of the ozone hole itself and the fact that a number of substances produced by man can destroy ozone. And if so, then the non-specialist has no doubt that it is human activity that is to blame for the depletion of the ozone layer - just look at the graphs of the growth of the hole and the increase in emissions of the corresponding substances into the atmosphere.
And here one more feature of the "ozone" myth emerges. For some reason, those who believe the above evidence completely forget that the coincidence of the two graphs in itself does not mean anything. After all, it may just be a coincidence. In order to have indisputable evidence of the anthropogenic theory of the origin of ozone holes, it is necessary to study not only the mechanism of ozone destruction by freons and other substances, but also the mechanism of the subsequent restoration of the layer.
Well, here comes the most interesting part. As soon as an interested non-specialist begins to study all these mechanisms (for which one does not need to sit in the library for days - it is enough to recall a few paragraphs from school textbooks on chemistry and geography), he immediately understands that this version is nothing more than a myth. And remembering the impact this myth had on world economy, having limited the production of freons, he immediately understands why he was created. However, let's consider the situation from the very beginning and in order.
From the course of chemistry, we remember that ozone is an allotropic modification of oxygen. In its molecules, not two O atoms, but three. Ozone can form in different ways, but the most common in nature is as follows: oxygen absorbs a portion of ultraviolet radiation with a wavelength of 175-200 nm and 280-315 nm and is converted into ozone. This is how the protective ozone layer formed in ancient times (somewhere 2-1.7 billion years ago), and this is how it continues to form to this day.
By the way, it follows from the above that in fact, almost half of the dangerous UV radiation absorbs oxygen, not ozone. Ozone is only a "by-product" of this process. However, its value lies in the fact that it also absorbs part of the ultraviolet - the one whose wavelength is from 200 to 280 nm. But what happens to the ozone itself? That's right - it turns back into oxygen. Thus, in the upper layers of the atmosphere there is a certain cyclic equilibrium process - one type of ultraviolet contributes to the conversion of ozone into oxygen, and the latter, absorbing another type of UV radiation, again turns into O 2.
From all this follows a simple and logical conclusion - in order to completely destroy the ozone layer, you need to deprive our atmosphere of oxygen. After all, no matter how much freons produced by people (hydrocarbons containing chlorine and bromine used as refrigerants and solvents), methane, hydrogen chloride and nitrogen monoxide destroy ozone molecules, ultraviolet irradiation of oxygen will restore the ozone layer again - after all, these substances will “turn off” it unable! As well as reducing the amount of oxygen in the atmosphere, since trees, grasses and algae produce it hundreds of thousands of times more than humanity - the aforementioned ozone depleters.
So, as you can see, not a single substance created by people is able to destroy the ozone layer while there is oxygen in the Earth's atmosphere, and the Sun emits ultraviolet radiation. But why then do ozone holes appear? I want to say right away that the term "hole" itself is not entirely correct - we are talking only about the thinning of the ozone layer in certain parts of the stratosphere, and not about its complete absence. Nevertheless, in order to answer the question posed, one should simply remember where exactly on the planet the largest and most stable ozone holes exist.
And here there is nothing to remember: the largest of the stable ozone holes is located directly above Antarctica, and the other, slightly smaller, is located above the Arctic. All other ozone holes of the Earth are unstable, they are quickly formed, but just as quickly "darned". Why, then, in the polar regions, the thinning of the ozone layer persists for such a long time? Yes, simply because in these places the polar night lasts for six months. And during this time, the atmosphere over the Arctic and Antarctic does not receive enough ultraviolet radiation that can turn oxygen into ozone.
Well, O 3, in turn, left without "replenishment", begins to quickly collapse - after all, it is a very unstable substance. That's why the ozone layer over the poles is pretty thinner, although the process goes with some delay - a visible hole appears at the beginning of summer, and disappears by the middle of winter. However, when the polar day comes, ozone begins to be produced again and the ozone hole is slowly "darned". True, not completely - all the same, the time of intense receipt of UV radiation in these parts is shorter than the period of its deficiency. That is why the ozone hole does not disappear.
But why, in this case, was a myth created and replicated? The answer to this question is not that simple, but very simple. The fact is that for the first time the presence of a permanent ozone hole over Antarctica was proven in 1985. And at the end of 1986, specialists American company DuPont (that is, DuPont) launched the production of a new class of refrigerants - fluorocarbons that do not contain chlorine. This greatly reduced the cost of production, but the new substance still had to be promoted to the market.
And here "DuPont" finances the dissemination in the media of the myth about the evil freons that spoil the ozone layer, which, on his order, was composed by a group of meteorologists. As a result, a frightened public began to demand that the authorities take action. And these measures were taken at the end of 1987, when a protocol was signed in Montreal to limit the production of substances that destroy the ozone layer. This led to the ruin of many freon companies, as well as to the fact that DuPont long years became a monopoly in the refrigerant market.
By the way, it was precisely the speed of the DuPont management's decision to use the ozone hole for their own purposes that led to the fact that the myth turned out to be so unfinished that it could be exposed by an ordinary schoolboy who did not skip chemistry and geography classes. If they had more time - you see, they would have composed a more convincing version. Nevertheless, even what was finally "born" by scientists commissioned by DuPont was able to convince many people.
This huge hole in the ozone layer of the earth was discovered in 1985, it appeared over Antarctica. In diameter, it is more than one thousand kilometers, and in area - about nine million kilometers squared.
Every year in the month of August, the hole disappears and it happens as if this huge ozone gap never existed.
Ozone hole - definition
An ozone hole is a decrease or complete absence of ozone concentration in the Earth's ozone layer. According to the report of the World Meteorological Organization and the theory generally accepted in science, a significant decrease in the ozone layer is caused by an ever-increasing anthropogenic factor - the release of bromine and chlorine-containing freons.
There is another hypothesis, according to which the very process of formation of holes in the ozone layer is natural and in no way connected with the results of the activity of human civilization.
A decrease in the concentration of ozone in the atmosphere causes a combination of factors. One of the main ones is the destruction of ozone molecules during reactions with various substances of natural and anthropogenic origin, as well as the absence sunlight and radiation during the polar winter. This includes the polar vortex, which is particularly stable and prevents the penetration of ozone from the latitudes of the polar region, and the resulting stratospheric polar clouds, the surface of the particles of which acts as a catalyst for the ozone decay reaction.
These factors are typical for Antarctica, and in the Arctic, the polar vortex is much weaker due to the fact that there is no continental surface. The temperature here is higher by a certain amount, in contrast to Antarctica. Polar stratospheric clouds are less common in the Arctic and tend to break up in early autumn.
What is Ozone?
Ozone is a poisonous substance that is harmful to humans. In small quantities, it has a very pleasant smell. To make sure of this, you can take a walk in the forest - a thunderstorm field - at the right time we will enjoy fresh air, but later it will be very bad health.
Under normal conditions, there is practically no ozone below the Earth's atmosphere - this substance is present in large quantities in the stratosphere, starting somewhere around 11 kilometers above the earth and extending up to 50-51 kilometers. The ozone layer lies just at the top of the catfish, that is, approximately 51 kilometers above the earth. This layer absorbs the deadly rays of the sun and thus protects our and not only our lives.
Before the discovery of ozone holes, ozone was considered a substance that poisoned the atmosphere. It was believed that the atmosphere was filled with ozone and that it was he who was the main culprit. greenhouse effect' with which something needs to be done.
In the present, on the contrary, humanity is trying to take steps to restore the ozone layer, as the ozone layer is becoming thinner throughout the Earth, and not just over Antarctica.
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