The stratosphere is one of the upper layers of the air envelope of our planet. It begins at an altitude of about 11 km above the ground. Passenger aircraft no longer fly here and clouds rarely form. In the stratosphere is the ozone layer of the Earth - a thin shell that protects the planet from the penetration of destructive ultraviolet radiation.
Planet air shell
The atmosphere is the gas shell of the Earth, adjacent the inner surface to the hydrosphere and the earth's crust. Its outer boundary gradually passes into outer space. The composition of the atmosphere includes gases: nitrogen, oxygen, argon, carbon dioxide, and so on, as well as impurities in the form of dust, water droplets, ice crystals, combustion products. The ratio of the main elements of the air shell remains constant. The exception is carbon dioxide and water - their amount in the atmosphere often changes.
Gas shell layers
The atmosphere is divided into several layers, located one above the other and having features in the composition:
boundary layer - directly adjacent to the surface of the planet, extends to a height of 1-2 km;
the troposphere is the second layer, the outer boundary is on average located at an altitude of 11 km, almost all atmospheric water vapor is concentrated here, clouds form, cyclones and anticyclones appear, and temperature increases with increasing altitude;
tropopause - a transition layer characterized by a cessation of temperature decrease;
the stratosphere is a layer extending to a height of 50 km and dividing into three zones: from 11 to 25 km the temperature changes slightly, from 25 to 40 - the temperature rises, from 40 to 50 - the temperature remains constant (stratopause);
the mesosphere extends to a height of 80-90 km;
the thermosphere reaches 700-800 km above sea level, here at an altitude of 100 km there is the Karmana line, which is taken as the boundary between the Earth’s atmosphere and space;
the exosphere is also called the scattering zone, here a very rarefied gas loses particles of matter, and they fly into space.
Temperature changes in the stratosphere
So, the stratosphere is a part of the gas shell of the planet following the troposphere. Here, the air temperature, constant throughout the tropopause, begins to change. The height of the stratosphere is approximately 40 km. The lower border is 11 km above sea level. Starting from this point, the temperature undergoes slight changes. At an altitude of 25 km, the heating rate begins to grow slowly. To the mark of 40 km above sea level, the temperature rises from -56.5º to + 0.8º. Further, it remains close to zero degrees up to an altitude of 50-55 km. The area between 40 and 55 kilometers is called the stratopause, since the temperature here does not change. It is a transition zone from the stratosphere to the mesosphere.
Features of the stratosphere
The stratosphere of the Earth contains about 20% of the mass of the entire atmosphere. The air here is so rarefied that it is impossible for a person to stay without a special spacesuit. This fact is one of the reasons why flights to the stratosphere began to be carried out only relatively recently.
Another feature of the gas shell of the planet at an altitude of 11-50 km is a very small amount of water vapor. For this reason, clouds almost never form in the stratosphere. For them, there is simply no building material. However, it is rarely possible to observe the so-called mother-of-pearl clouds that “decorate” the stratosphere (photo below) at an altitude of 20-30 km above sea level. Thin, as if glowing from the inside, formations can be observed after sunset or before sunrise. In shape, pearly clouds are similar to cirrus or cirrocumulus.
Earth's ozone layer
The main distinguishing feature of the stratosphere is the maximum concentration of ozone in the entire atmosphere. It is formed under the influence of sunlight and protects all life on the planet from their destructive radiation. The ozone layer of the Earth is located at an altitude of 20-25 km above sea level. O 3 molecules are distributed throughout the stratosphere and even exist on the surface of the planet, however, at this level their highest concentration is observed.
It should be noted that the ozone layer of the Earth is only 3-4 mm. Such will be its thickness if particles of this gas are placed under normal pressure conditions, for example, at the surface of the planet. Ozone is formed as a result of the decay of an oxygen molecule by ultraviolet radiation into two atoms. One of them combines with a "full" molecule and ozone - O 3 is formed .
Dangerous defender
Ozone molecules absorb ultraviolet radiation with a wavelength shorter than 0.1-0.2 microns. This is its protective role. A thin layer of bluish gas prevents the penetration of solar radiation on Earth, harmful to living organisms.
With a stream of wind, ozone falls close to the surface of the planet. It is formed on Earth during a thunderstorm, the work of photocopiers or X-rays. Interestingly, a high concentration of ozone is harmful to humans. It is formed by the action of sunlight in highly gassed areas. Arriving in the conditions of the so-called ozone smog is life threatening. Bluish gas can destroy the lungs. Affects its presence on plants - they cease to develop normally.
Ozone Depletion
The problem of ozone holes has been actively discussed in the scientific community since about the 70s of the last century. It is now known that atmospheric pollution, the industrial use of freons and some other compounds, the destruction of forests, the launch of space rockets and high-altitude aviation lead to the destruction of the protective shield. The international community has adopted a number of agreements designed to reduce the production of harmful substances. First of all, we are talking about freons, which are used to create aerosols, refrigeration units, fire extinguishers, disposable tableware, and so on.
Moreover, there is evidence to suggest that the formation of ozone holes occurs for natural reasons. Harmful substances enter the atmosphere as a result of volcanic eruptions and earthquakes from faults in the oceanic crust. Today, the question of the main role of man in the destruction of the ozone layer for a number of scientists remains controversial.
Stratosphere Flights
The development of the stratosphere began in the 30s of the last century. Today, combat and supersonic commercial aircraft rise to a height of 20 km. Marks 40 km above sea level reach the weather balloons. The record height reached by an unmanned aerostat is 51.8 km.
Gradually master this part of the air shell and fans of extreme sports. In 2012, the Austrian parachutist Felix Baumgartner made a jump from the stratosphere from an altitude of almost 39 km. Overcoming the sound barrier during the flight , he landed safely. Baumgartner’s record was broken by Google’s vice president Alan Eustace. In 15 minutes he flew, also reaching the speed of sound, 40 km.
Thus, today the stratosphere is a more explored layer of the atmosphere than at the beginning of the last century. However, the future of the ozone layer, without which life on Earth would not have arisen, is still not very clear. While countries are reducing freon production, some scientists say that it will not be of particular benefit, at least at such a pace, while others that it is not at all necessary, since the bulk of the harmful substances are formed naturally. Who is right - time will judge.