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 radiation reaching the earth's surface. Unlike ordinary oxygen, ozone is unstable; it easily transforms into the 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 concentration in the surface layers of air under normal conditions, these features have practically no effect on 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 hard (short-wave) ultraviolet (UV) radiation from the Sun. Hard UV quanta have energy sufficient to break some chemical bonds, therefore it is classified as ionizing radiation. Like other radiations of this kind, x-rays 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. When exposed to moderate radiation, it disintegrates, absorbing the energy of this radiation. Thus, this cyclical process “eats” dangerous ultraviolet radiation.

Ozone molecules, like oxygen, are electrically neutral, i.e. don't carry electric 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, practically coincides with the ozone layer.

In the polar zones, where power lines magnetic field The Earth is closed on its surface, the distortions of the ionosphere are very significant. The number of ions, including ionized oxygen, in the upper layers of the atmosphere of the polar zones is reduced. But the main reason for the low ozone content in the polar region is the low intensity of solar radiation, which falls even during the polar day at small angles to the horizon, and is completely absent during the polar night. The area of polar “holes” in the ozone layer is a reliable indicator of changes in the total ozone content in the atmosphere.

The ozone content in the atmosphere fluctuates due to many natural reasons. Periodic oscillations are associated with cycles 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. Due to the high, hurricane-like speeds of air flows in the stratosphere, ozone-depleting substances are carried over large areas. Not only ozone depleters are transported, but also ozone itself, so disturbances in ozone concentration quickly spread over large areas, and local small “holes” in the ozone shield, caused, for example, by a rocket launch, heal relatively quickly. Only in the polar regions is the air inactive, as a result of which the disappearance of ozone there is not compensated by its import from other latitudes, and the polar “ozone holes,” especially at the South Pole, are very stable.

Sources of ozone layer destruction. Among the ozone layer depleters are:

1) Freons.

Ozone is destroyed by chlorine compounds known as freons, which, also destroyed by solar radiation, release chlorine, which “tears off” the “third” atom from ozone molecules. Chlorine does not form compounds, but serves as a “breaking” catalyst. Thus, one chlorine atom can “destroy” a lot of ozone. It is believed that chlorine compounds can 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-50s.

There is no consensus on the question of how much humans are to blame for the formation of “ozone holes.”

On the one hand, yes, he is certainly guilty. The production of compounds that lead to ozone depletion should be minimized, or better yet stopped altogether. That is, to abandon an entire industry sector with a turnover of many billions of dollars. And if you don’t refuse, then transfer it to “safe” rails, which also costs money.

The point of view of skeptics: human influence on atmospheric processes, for all its destructiveness on a local level, is negligible on a planetary scale. The Greens' anti-freon campaign has a completely transparent economic and political background: with its help, large American corporations (DuPont, for example) are strangling their foreign competitors by imposing agreements on "protection" environment"at the state level and forcibly introducing a new technological revolution, which is weaker in economically states are unable to withstand.

2) High altitude aircraft.

It's not just the power of an airplane's engine that matters, but also the altitude at which it flies and releases ozone-depleting nitrogen oxides. The higher the nitrous oxide or oxide is formed, the more destructive it is to ozone.

The total amount of nitrogen oxide that is emitted 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 from military aircraft, the number of which amounts to tens of thousands. They fly primarily at altitudes in 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 fixed nitrogen is also carried out by microorganisms in the upper layer of oceans and seas. The denitrification process is directly related to the amount of fixed nitrogen in the soil. Thus, you can be sure that with an increase in the amount of mineral fertilizers applied to the soil, the amount of nitrous oxide N2O produced 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. A temperature of 60,000 K is established within a few seconds after a nuclear explosion. This is the energy of the fireball. In a highly heated atmosphere, such transformations occur chemical substances, which under normal conditions either do not occur or occur very slowly. As for ozone and its disappearance, the most dangerous for it are the nitrogen oxides formed during these transformations. Thus, during the period from 1952 to 1971, as a result of nuclear explosions, about 3 million tons of nitrogen oxides were formed in the atmosphere. Further fate They are as follows: as a result of mixing the atmosphere, they fall to different heights, including into the atmosphere. There they enter into 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 and contribute to the formation of smog in it, but they 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 annually! This figure suggests that this source of ozone destruction 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 an analysis of data from the Halley Bay ozone station (76°S). A decrease in ozone was also observed by this service in the Argentine Islands (65 degrees S).

From August 28 to September 29, 1987, 13 flights of the laboratory aircraft were carried out over Antarctica. The experiment made it possible to register the birth of the ozone hole. Its dimensions were obtained. Studies have shown that the greatest decrease in ozone occurred at altitudes of 14 - 19 km. The devices were registered here greatest number aerosols (aerosol layers). It turned out that the more aerosols there are at a given altitude, the less ozone there is. The aircraft laboratory recorded 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 levels with pressure from 100 to 25 hPa, and in December the range of altitudes at which it is observed expands.

Many experiments measured not only the amount of ozone and other small components of the atmosphere, but also temperature. The closest connection 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 carried out measurements in Antarctica in the winter and early spring of 1987 of ozone and other small components of the atmosphere (HCl, HF, NO, NO2, HNO3, ClONO2, N2O, CH4) using a special spectrometer. 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, but also other small components that influence the destruction of ozone, changed sharply. 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 occurs 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 ozone concentration occurs (at least 80% of this decrease).

These reactions occur on the surface of the particles that make up the polar stratospheric clouds. This means that the larger the area of this surface, that is, the more particles of stratospheric clouds, and therefore the clouds themselves, the faster the ozone ultimately decays, and therefore the more efficiently the ozone hole is formed.

The occurrence of ozone holes in the polar regions occurs due to the influence of a number of factors. Ozone concentrations decrease as a result of exposure to substances of natural and anthropogenic origin, as well as due to a lack of solar radiation during the polar winter. The main anthropogenic factor causing the occurrence of ozone holes in the polar regions occurs due to the influence of a number of factors. Ozone concentrations decrease as a result of exposure to substances of natural and anthropogenic origin, as well as due to a lack of solar radiation during the polar winter. The main anthropogenic factor causing a decrease in ozone concentration is the release of chlorine- and bromine-containing freons. In addition, extremely low temperatures in the polar regions cause the formation of so-called polar stratospheric clouds, which, in combination with polar vortexes, act as catalysts in the ozone decay reaction, that is, they simply kill ozone.

Sources of destruction

Among the ozone layer depleters are:

1) Freons.

The ozone hole over Antarctica, which increases in size in the spring and decreases in the fall, was discovered in 1985. The discovery of meteorologists caused a chain of economic consequences. The fact is that the existence of the “hole” was blamed on the chemical industry, which produces substances containing freons that contribute to the destruction of ozone (from deodorants to refrigeration units). There is no consensus on the question of how much humans are to blame for the formation of “ozone holes.” On the one hand, yes, he is certainly guilty. The production of compounds that lead to ozone depletion should be minimized, or better yet stopped altogether. That is, to abandon an entire industry sector with a turnover of many billions of dollars. And if you don’t refuse, then transfer it to “safe” rails, which also costs money.

The point of view of skeptics: human influence on atmospheric processes, for all its destructiveness on a local level, is negligible on a planetary scale. The anti-freon campaign of the “greens” has a completely transparent economic and political background: with its help, large American corporations (DuPont, for example) are strangling their foreign competitors, imposing agreements on “environmental protection” at the state level and forcibly introducing a new technological stage that is more economically weak states are unable 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 the combustion chambers of turbojet engines of high-altitude aircraft. Nitrogen oxides are formed from the nitrogen and oxygen that are found there. The higher the temperature, i.e., the greater the engine power, the greater the rate of formation of nitrogen oxides. It's not just the power of an airplane's engine that matters, but also the altitude at which it flies and releases ozone-depleting nitrogen oxides. The higher the nitrous oxide or oxide is formed, the more destructive it is to ozone. The total amount of nitrogen oxide that is emitted 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 from military aircraft, the number of which amounts to tens of thousands. They fly primarily at altitudes in 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 fixed nitrogen is also carried out by microorganisms in the upper layer of oceans and seas. The denitrification process is directly related to the amount of fixed nitrogen in the soil. Thus, you 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. A temperature of 6000 0 C is established within a few seconds after a nuclear explosion. This is the energy of the fireball. In a highly heated atmosphere, transformations of chemical substances occur that either do not occur under normal conditions, or proceed very slowly. As for ozone and its disappearance, the most dangerous for it are the nitrogen oxides formed during these transformations. Thus, during the period from 1952 to 1971, as a result of nuclear explosions, about 3 million tons of nitrogen oxides were formed in the atmosphere. Their further fate is as follows: as a result of atmospheric mixing, they end up at different heights, including the atmosphere. There they enter into chemical reactions with the participation of ozone, leading to its destruction.

5) Fuel combustion.

N 2 + O + M = N 2 O + M,

2NH 3 + 2O 2 =N 2 O = 3H 2.

The scale of this phenomenon is very significant. In this way, approximately 3 million tons of nitrous oxide are formed in the atmosphere annually! This figure suggests that it is a source of ozone destruction.

Conclusion: Sources of destruction are: freons, high-altitude aircraft, mineral fertilizers, nuclear explosions, fuel combustion.

An important environmental issue of our time is ozone holes. The atmosphere prevents the destruction of the ecosystem; it protects it from ultraviolet radiation, radiation and debris from space. However, at the end of the 20th century, scientists discovered an ozone hole in Antarctica, which represented a thinning of the ozone layer so necessary to protect the earth's surface.

Ozone holes, the causes and consequences of which have already been well studied by experts, pose a threat to the lives of people, animals and plants.

What are ozone holes?

The ozone layer is part of the stratosphere. It spreads at altitudes from 12 to 30 km. The higher the ozone content, the more protected the Earth is from harmful effects sun rays. Interesting fact: They first started talking about the thinning of the protective shell in 1957. The ozone hole has become a threat to life on Earth.

The essence of the problem

The source of ozone formation is oxygen, which is exposed to ultraviolet radiation. This reaction results in the planet being enveloped in a layer of gas through which radiation does not penetrate. The problem of thinning the ozone layer began to receive much attention in the 1980s. 20th century. The discoverer of the phenomenon is deservedly considered to be the British scientist J. Farman.

In such places there is a decrease in the amount of ozone. Its concentration is reduced to 30-35%. Through these areas, ultraviolet rays easily penetrate the atmosphere and burn all life on the planet.

Locations where holes appear

J. Farmen, as part of a research group in 1985, discovered the largest OD over Antarctica. Moreover, this anomaly appeared in the summer, in August. In winter, in December-January, the gas began to thicken and tightened the hole formed in the summer so much that it completely disappeared. Continuing their research, scientists found many other small ODs. The holes were localized over the Arctic and existed for approximately 7 days, after which the shell was restored.

Now the map of ozone holes is constantly changing, due to the time of year. Most often they form during warm periods. The critical points where thinning of the shell is observed are located at an altitude of 19 km above the Earth.

How are ODs formed?

There are several reasons for the appearance of OD. One of them, according to experts, is due to natural natural phenomena, which are observed at the Earth's poles. The theoretical justification for the presence of this anomaly comes down to the existence of polar nights, during which the sun's rays do not reach the Earth's surface, which prevents the formation of ozone. This leads to the appearance of stratospheric clouds, with which small ice crystals containing chlorine are transported. This substance has a destructive effect on the atmosphere.

Another reason that negatively affects the condition of the protective shell is periods of volcanic activity that are observed on the surface of the Earth. During volcanic eruptions, intense emissions of combustion products occurred and still occur, which contribute to the destruction of layers of the stratosphere.

Freon, which is a group of hydrocarbons with fluorine atoms, also has a strong negative effect on the integrity of the protective layers.

The ozone hole is formed as a result of the destruction of ozone under the influence of chemical compounds emitted into the atmosphere as a result of anthropogenic factors.

Major ozone layer depleters

Technological progress and ML are inextricably linked with each other. The main source of harmful substances that destroy ozone are various factories, factories, gas power plants, etc. Their emissions, containing elements such as hydrogen, bromine, oxygen, combustion products, entering the atmosphere, reduce the amount of ozone, which leads to to thinning of the protective shell.

A large amount of energy that is released during nuclear tests, accompanied by the release of nitrogen. This substance reacts with ozone, destroying it. Experts have calculated that between 1950 and 1970, more than 3 million tons of nitrogen were released into the atmosphere as a result of explosions at nuclear test sites.

Oxides of this element are produced in jet engines. As engine power increases, the temperature in the combustion chambers increases. Every year, more than 1 million tons of nitrogen are released into the atmosphere. 1/3 of this amount comes from the operation of jet engines.

Mineral fertilizers, used in large quantities in agriculture, also have a detrimental effect on ozone. Chemical elements, included in them, reacting with bacteria in the soil, produce nitrogen, which is subsequently oxidized.

Hypotheses about the natural origin of OA

Russian researchers point out that the thinning of the ozone layer is a phenomenon that was generated only by natural causes. Thus, in 1999 it was published scientific work, authored by A.P. Kapitsa and A.A. Gavrilov. It was published on the basis of the Moscow State University NPO “Typhoon”. According to Russian scientists, a decrease in the ozone layer was observed on Earth even before it was discovered by their English colleagues.

A.P. Kapitsa and A.A. Gavrilov experimentally determined that there are a number of natural factors that contribute to a decrease in the amount of ozone in the stratosphere, and the impact of these factors is constantly increasing. In such places an ozone hole can form. Its occurrence is caused by natural phenomena, and not by anthropogenic influence, which, although it harms the environment, is to a lesser extent than expected.

What consequences could depletion of the ozone layer have for humanity?

Environmentalists see the danger of reducing the amount of ozone in the fact that the stratosphere will freely transmit ultraviolet rays harmful to all living things. This impact also affects humans: the number of cancer diseases is growing. Scientists have concluded that if ozone concentrations decrease by even 1% more, the number of people with cancer will increase by 7,000 people per year. The first place will be taken by skin diseases, and then by cancer diseases that affect other organs of the human body.

Another consequence of ML is the reduction of vegetation on Earth. A decrease in this type of cover will lead to the death of animals on the earth's surface and, as a consequence, in the depths of the sea. Already, the extinction of some animal species is due to processes occurring in the layers of the atmosphere.

Scientists are well aware of the dangers of OD, so they call for measures to be taken to restore the ozone layer, otherwise this natural disaster could lead to unpredictable consequences on Earth.

Forecasts for the future

OA is considered one of the most important environmental issues on a global scale. Scientists in many countries are constantly monitoring the processes occurring in the stratosphere, noting an increase or decrease in the ozone layer, as well as determining the factors that influence this. It is interesting that in some regions one can notice a positive trend in the restoration of an element necessary for the Earth.

The OD was largest over Antarctica in 2000. Over the past period, it has not increased; on the contrary, there is a tendency to delay it. Its area has decreased by more than 4 million km². This was influenced by an international agreement that was signed in 1987 in Montreal. According to this document, all countries must minimize the emission of nitrogen and other harmful substances into the atmosphere and reduce transport. China has achieved the greatest success in this matter. The government introduced quotas on car production.

Another factor that has a beneficial effect on solving this environmental situation is the use of alternative energy sources, such as wind or solar power.

Most of the forecasts and studies concerning the consequences of the expansion of OA are published in the scientific journal Science. Various conferences dedicated to this issue are held annually. Thus, the conclusions of the Paris Climate Conference sound optimistic.

The hole over Antarctica will disappear by 2021 if ozone layer will increase due to the reduction of harmful emissions into the atmosphere.

How to prevent ozone layer depletion?

Scientists are busy not only with the restoration of the depleted ozone shell, but also are looking for ways to prevent the occurrence of OD. To do this, it is necessary to combat the production of substances containing chlorofluorocarbons on a global scale. This decision was made in Montreal in 1989. The entire world community should look for preventative ways to deplete the ozone layer and solutions, since the existence of holes affects the ecology of the entire Earth.

To reduce the risk of new holes appearing in the ozone shell, it is necessary to continuously scientific developments in order to identify and eliminate such methods of production and energy generation that will not cause harm to the environment. There is an urgent need to begin installing treatment facilities everywhere on the smoking chimneys of factories and factories, and to replace chemical fertilizers with organic ones. An important step The protection of the ozone layer will include the transition of the transport system running on petroleum products to electricity.

Can the ozone layer be restored?

Methods

Preventing harmful emissions is not the only way to preserve the Earth's protective layer. One of effective methods ecologists see it as spraying artificially created ozone at an altitude of 15-30 km above the Earth's surface using special aircraft. And this is a good solution, because it will fill the voids in the stratosphere.

However this method has a number of disadvantages. It is expensive, so it can only be applied if financial resources from several countries are attracted. In addition, a small amount of ozone can be delivered to the OD site at a time; the process of transporting it is complex and poses a danger to the people carrying it out.

Myths

The ozone hole has given rise to some misconceptions. For example, many believe that thinning occurs only in Antarctica. However, ODs can appear anywhere on Earth. Some industrialists tried to reduce the importance of the environmental issue because they were afraid of losing income from their enterprises. However, it was not possible to minimize the scale of the disaster.

There is a false idea that freons have a large mass, and therefore cannot reach the stratosphere, settling in the ground without causing harm to it. But once even in the lower layers, these substances can mix with other elements and, together with them, rise to the protective layer.

IN Lately Increasingly, the public is concerned about environmental issues - protecting the environment, animals, reducing the amount of harmful and dangerous emissions. Surely everyone has also heard about what an ozone hole is, and that there are a lot of them in the modern stratosphere of the Earth. This is true.

Modern anthropogenic activities and technological development threaten the existence of animals and plants on Earth, as well as the very lives of people.

The ozone layer is the protective shell of the blue planet, which is located in the stratosphere. Its height is approximately twenty-five kilometers from the earth's surface. And this layer is formed from oxygen, which under the influence of solar radiation undergoes chemical transformations. A local decrease in ozone concentration (in common parlance this is the well-known “hole”) is currently caused by many reasons. First of all, this is, of course, human activity (both production and everyday life). There are, however, opinions that the ozone layer is destroyed under the influence of exclusively natural phenomena not related to humans.

Anthropogenic influence

Having understood what the ozone hole is, it is necessary to find out what kind of human activity contributes to its appearance. First of all, these are aerosols. Every day we use deodorants, hairsprays, eau de toilette with spray bottles and often do not think about the fact that this has a detrimental effect on the protective layer of the planet.

The fact is that the compounds that are present in the cans we are used to (including bromine and chlorine) readily react with oxygen atoms. Therefore, the ozone layer is destroyed, turning after such chemical reactions into completely useless (and often harmful) substances.

Destructive compounds for the ozone layer are also present in air conditioners, which are life-saving in the summer heat, as well as in cooling equipment. Widespread human industrial activity also weakens the earth's defenses. It is oppressed by industrial water (some of the harmful substances evaporate over time), polluting the stratosphere and cars. The latter, as statistics show, is becoming more and more numerous every year. Negatively affects the ozone layer and

Natural influence

Knowing what an ozone hole is, you also need to have an idea of how many there are above the surface of our planet. The answer is disappointing: there are many gaps in earthly defenses. They are small and often represent not a hole, but a very thin remaining layer of ozone. However, there are also two huge unprotected spaces. This is the Arctic and Antarctic ozone hole.

The stratosphere above the Earth's poles contains almost no protective layer at all. What is this connected with? There are no cars or industrial production there. It's all about natural influence, the second reason. Polar vortexes arise when warm and cold air currents collide. These gas formations contain large quantities of nitric acid, which, when exposed to very low temperatures, reacts with ozone.

Environmentalists began to sound the alarm only in the twentieth century. Destructive ones that make their way to the ground without encountering an ozone barrier can cause skin cancer in humans, as well as the death of many animals and plants (primarily marine ones). Thus, international organizations have banned almost all compounds that destroy the protective layer of our planet. It is believed that even if humanity abruptly stops any negative impact on ozone in the stratosphere, the currently existing holes will not disappear very soon. This is explained by the fact that freons that have already made their way to the top are able to independently exist in the atmosphere for decades to come.

Ozone holes - “children” of stratospheric vortices

Although there is little ozone in the modern atmosphere - no more than one three-millionth of the other gases - its role is extremely large: it delays hard ultraviolet radiation(short-wavelength part of the solar spectrum), destroying proteins and nucleic acids. In addition, stratospheric ozone is an important climatic factor that determines short-term and local weather changes.

The rate of ozone destruction reactions depends on catalysts, which can be either natural atmospheric oxides or substances released into the atmosphere as a result of natural disasters (for example, powerful volcanic eruptions). However, in the second half of the last century, it was discovered that substances of industrial origin can also serve as catalysts for ozone destruction reactions, and humanity became seriously worried...

Ozone (O3) is a relatively rare molecular form of oxygen consisting of three atoms. Although there is little ozone in the modern atmosphere - no more than one three-millionth of the other gases - its role is extremely large: it blocks hard ultraviolet radiation (the short-wave part of the solar spectrum), which destroys proteins and nucleic acids. Therefore, before the advent of photosynthesis - and, accordingly, free oxygen and the ozone layer in the atmosphere - life could only exist in water.

In addition, stratospheric ozone is an important climatic factor that determines short-term and local weather changes. By absorbing solar radiation and transferring energy to other gases, ozone heats the stratosphere and thereby regulates the nature of planetary thermal and circular processes throughout the atmosphere.

Unstable ozone molecules are formed and disintegrated under natural conditions under the influence of various living and inanimate nature, and in the course of long evolution this process has come to some dynamic equilibrium. The rate of ozone destruction reactions depends on catalysts, which can be either natural atmospheric oxides or substances released into the atmosphere as a result of natural disasters (for example, powerful volcanic eruptions).

However, in the second half of the last century, it was discovered that substances of industrial origin can also serve as catalysts for ozone destruction reactions, and humanity was seriously worried. Public opinion was especially excited by the discovery of the so-called ozone “hole” over Antarctica.

"Hole" over Antarctica

A noticeable loss of the ozone layer over Antarctica - the ozone hole - was first discovered back in 1957, during the International Geophysical Year. Her real story began 28 years later with an article in the May issue of the magazine Nature, where it was suggested that the cause of the anomalous spring TO minimum over Antarctica is industrial (including freons) atmospheric pollution (Farman et al., 1985).

It was found that the ozone hole over Antarctica usually appears once every two years, lasts about three months, and then disappears. It is not a through hole, as it might seem, but a depression, so it is more correct to talk about “sagging of the ozone layer.” Unfortunately, all subsequent studies of the ozone hole were mainly aimed at proving its anthropogenic origin (Roan, 1989).

ONE MILLIMETER OF OZONE Atmospheric ozone is a spherical layer about 90 km thick above the Earth's surface, and the ozone in it is unevenly distributed. Most of this gas is concentrated at an altitude of 26–27 km in the tropics, at an altitude of 20–21 km in the middle latitudes, and at an altitude of 15–17 km in the polar regions.
Total ozone content (TOC), i.e. the amount of ozone in the atmospheric column at a particular point, is measured by the absorption and emission of solar radiation. The so-called Dobson unit (D.U.) is used as a unit of measurement, corresponding to the thickness of the layer of pure ozone at normal pressure (760 mm Hg) and temperature 0 ° C. One hundred Dobson units correspond to the thickness of the ozone layer of 1 mm.
The amount of ozone in the atmosphere experiences daily, seasonal, annual and long-term fluctuations. With a global average TO of 290 DU, the thickness of the ozone layer varies widely - from 90 to 760 DU.
The ozone content in the atmosphere is monitored by a worldwide network of about one hundred and fifty ground-based ozonometer stations, very unevenly distributed over the land area. Such a network is practically unable to detect anomalies in the global distribution of ozone, even if the linear size of such anomalies reaches thousands of kilometers. More detailed data on ozone is obtained using optical equipment installed on artificial satellites Earth.
It should be noted that a slight decrease in total ozone (TO) in itself is not catastrophic, especially at middle and high latitudes, because clouds and aerosols can also absorb ultraviolet radiation. In Central Siberia, where the number of cloudy days is high, there is even a deficiency of ultraviolet radiation (about 45% of the medical norm).

Today, there are different hypotheses regarding the chemical and dynamic mechanisms of ozone hole formation. However, many known facts do not fit into the chemical anthropogenic theory. For example, an increase in stratospheric ozone levels in certain geographic regions.

Here is the most “naive” question: why does a hole form in southern hemisphere, although freons are produced in the northern one, despite the fact that it is unknown whether there is air communication between the hemispheres at this time?

A noticeable loss of the ozone layer over Antarctica was first discovered back in 1957, and three decades later the blame was placed on industry

None of the existing theories is based on large-scale detailed measurements of TOC and studies of processes occurring in the stratosphere. It was possible to answer the question about the degree of isolation of the polar stratosphere over Antarctica, as well as a number of other questions related to the problem of the formation of ozone holes, only with the help of a new method of tracking the movements of air flows proposed by V. B. Kashkin (Kashkin, Sukhinin, 2001; Kashkin et al., 2002).

Air flows in the troposphere (up to a height of 10 km) have been tracked for a long time by observing the translational and rotational movements of clouds. Ozone, in fact, is also a huge “cloud” over the entire surface of the Earth, and by changes in its density we can judge the movement of air masses above 10 km, just as we know the direction of the wind by looking at a cloudy sky on a cloudy day. For these purposes, ozone density should be measured at spatial grid points at a certain time interval, for example, every 24 hours. By tracking how the ozone field has changed, you can estimate the angle of its rotation per day, the direction and speed of movement.

BAN ON FREONS - WHO WON? In 1973, Americans S. Rowland and M. Molina discovered that chlorine atoms released from certain volatile artificial chemicals under the influence of solar radiation can destroy stratospheric ozone. They assigned the leading role in this process to the so-called freons (chlorofluorocarbons), which at that time were widely used in household refrigerators, air conditioners, as a propellant gas in aerosols, etc. In 1995, these scientists, together with P. Crutzen were awarded for their discovery Nobel Prize in chemistry.
Restrictions have been placed on the production and use of chlorofluorocarbons and other ozone-depleting substances. The Montreal Protocol on Substances that Deplete the Ozone Layer, which controls 95 compounds, is currently signed by more than 180 states. In law Russian Federation on environmental protection natural environment There is also a special article dedicated to
protection of the Earth's ozone layer. The ban on the production and consumption of ozone-depleting substances had serious economic and political consequences. After all, freons have a lot of advantages: they are low-toxic compared to other refrigerants, chemically stable, non-flammable and compatible with many materials. Therefore, chemical industry leaders, especially in the United States, were initially against the ban. However, later the DuPont concern joined the ban, proposing the use of hydrochlorofluorocarbons and hydrofluorocarbons as an alternative to freons.
IN Western countries a “boom” began with the replacement of old refrigerators and air conditioners with new ones that do not contain ozone-depleting substances, although such technical devices have lower efficiency, are less reliable, consume more energy and are also more expensive. Companies that were the first to use new refrigerants benefited and made huge profits. In the United States alone, losses from the ban on chlorofluorocarbons amounted to tens, if not more, of billions of dollars. An opinion has emerged that the so-called ozone conservation policy could have been inspired by the owners of large chemical corporations in order to strengthen their monopoly position in the world market

Using a new method, the dynamics of the ozone layer was studied in 2000, when a record large ozone hole was observed over Antarctica (Kashkin et al., 2002). To do this, they used satellite data on ozone density throughout the southern hemisphere, from the equator to the pole. As a result, it was found that the ozone content is minimal in the center of the funnel of the so-called circumpolar vortex, which formed above the pole, which we will discuss in detail below. Based on these data, a hypothesis was put forward about the natural mechanism for the formation of ozone “holes”.

Global dynamics of the stratosphere: a hypothesis

Circumpolar vortices are formed when stratospheric air masses move in the meridional and latitudinal directions. How does this happen? At the warm equator the stratosphere is higher, and at the cold pole it is lower. Air currents (along with ozone) roll down from the stratosphere as if down a hill, and move faster and faster from the equator to the pole. Movement from west to east occurs under the influence of the Coriolis force associated with the rotation of the Earth. As a result, air flows seem to be wound, like threads on a spindle, on the southern and northern hemispheres.

The “spindle” of air masses rotates throughout the year in both hemispheres, but is more pronounced at the end of winter and beginning of spring, because the height of the stratosphere at the equator remains almost unchanged throughout the year, and at the poles it is higher in summer and lower in winter, when it is especially Cold.

The ozone layer in mid-latitudes is created by a powerful influx from the equator, as well as by photochemical reactions that occur in situ. But ozone in the polar region owes its origin mainly to the equator and mid-latitudes, and its content there is quite low. Photochemical reactions at the pole, where the sun's rays fall at a low angle, proceed slowly, and a significant part of the ozone coming from the equator manages to be destroyed along the way.

Based on satellite data on ozone density, a natural mechanism for the formation of ozone holes was hypothesized

But air masses do not always move this way. In the coldest winters, when the stratosphere above the pole drops very low above the Earth's surface and the “slide” becomes especially steep, the situation changes. The stratospheric currents roll down so quickly that the effect is familiar to anyone who has watched water flow through a hole in a bathtub. Having reached a certain speed, the water begins to rotate rapidly, and a characteristic funnel is formed around the hole, created by centrifugal force.

Something similar happens in the global dynamics of stratospheric flows. When stratospheric air flows gain sufficiently high speed, centrifugal force begins to push them away from the poles towards the middle latitudes. As a result, air masses move from the equator and from the pole towards each other, which leads to the formation of a rapidly rotating vortex “shaft” in the mid-latitude region.

The exchange of air between the equatorial and polar regions ceases; ozone does not flow from the equator and from the middle latitudes to the pole. In addition, the ozone remaining at the pole, as in a centrifuge, is pressed toward the middle latitudes by centrifugal force, since it is heavier than air. As a result, the ozone concentration inside the funnel drops sharply - an ozone “hole” is formed above the pole, and in the middle latitudes - a region of high ozone content corresponding to the “shaft” of the circumpolar vortex.

In spring, the Antarctic stratosphere warms up and rises higher - the funnel disappears. Air communication between middle and high latitudes is restored, and photochemical reactions of ozone formation are accelerated. The ozone hole is disappearing before another particularly cold winter at the South Pole.

What's in the Arctic?

Although the dynamics of stratospheric flows and, accordingly, the ozone layer in the northern and southern hemispheres are generally similar, the ozone hole only appears from time to time over the South Pole. There are no ozone holes over the North Pole because winters there are milder and the stratosphere never drops low enough for air currents to reach the speed necessary to form a hole.

Although the circumpolar vortex also forms in the northern hemisphere, ozone holes are not observed there due to milder winters than in the southern hemisphere

There is one more thing important difference. In the southern hemisphere, the circumpolar vortex rotates almost twice as fast as in the northern hemisphere. And this is not surprising: Antarctica is surrounded by seas and there is a circumpolar sea current around it - essentially, giant masses of water and air rotate together. The picture is different in the northern hemisphere: in the middle latitudes there are continents with mountain ranges, and the friction of the air mass on the earth's surface does not allow the circumpolar vortex to gain a sufficiently high speed.

However, in the middle latitudes of the northern hemisphere, small ozone “holes” of a different origin sometimes appear. Where do they come from? The movement of air in the stratosphere of the mid-latitudes of the mountainous northern hemisphere resembles the movement of water in a shallow stream with a rocky bottom, when numerous whirlpools form on the surface of the water. In the middle latitudes of the northern hemisphere, the role of the bottom surface topography is played by temperature differences at the boundaries of continents and oceans, mountain ranges and plains.

A sharp change in temperature on the Earth's surface leads to the formation of vertical flows in the troposphere. Stratospheric winds, encountering these flows, create vortices that can rotate in both directions with equal probability. Inside them, areas with low ozone content appear, that is, ozone holes that are much smaller in size than at the South Pole. And it should be noted that such vortices with different directions of rotation were discovered on the first attempt.

Thus, the dynamics of stratospheric air flows, which we tracked by observing the ozone cloud, allows us to provide a plausible explanation for the mechanism of formation of the ozone hole over Antarctica. Apparently, similar changes in the ozone layer, caused by aerodynamic phenomena in the stratosphere, took place long before the advent of man.

All of the above does not mean that freons and other gases of industrial origin do not have a destructive effect on the ozone layer. However, scientists have yet to find out what the relationship between natural and anthropogenic factors is that influence the formation of ozone holes; it is unacceptable to draw hasty conclusions on such important issues.