What is the ozone layer?

Ozone in natureThe ozone layer - a part of the stratosphere at an altitude of 12 to 50 km (in the tropical latitudes of 25-30 km, moderate 20-25, 15-20 in the polar), which under the influence of ultraviolet radiation from the sun molecular oxygen (O2) is dissociated into atoms, which then combine with other O2 molecules, forming ozone (O3).

Relatively high concentrations of ozone (about 8 ml / m³) absorbs harmful ultraviolet rays and protects all living on land from deadly radiation.

Thanks to the air heating due to the absorption of sunlight by ozone temperature inversion occurs, ie, an increase in temperature with height. Thus the troposphere and stratosphere are separated by the tropopause and mixing of air between the layers of the atmosphere is difficult.

Moreover, if it were not for the ozone layer, life could not even get out of the oceans and highly developed forms of life such as mammals, including humans, would not have arisen. The highest density of ozone is found at an altitude of 20-25 km, the largest part of the total volume – at an altitude of 40 km.

If it were possible to extract all the ozone in the atmosphere, and squeezed under normal pressure, the result would leave the layer covering the surface of the Earth thickness of 3 mm. For comparison, all compressed under normal pressure of the atmosphere is a layer of 8 km.

Discoverer of the ozone layer were Ch. Fabry and H. Buisson, French physicists. In 1912, they succeeded with the help of spectroscopic measurements of ultraviolet radiation to prove the existence of ozone in remote from the Earth atmosphere.


Ozone layer. Photo:kconnors

Ozone in the atmosphere

(a modification of the oxygen molecule 03) is formed under the influence of short-wavelength ultraviolet (UV) radiation from the sun. You can verify this by experience, if you turn the UV lamp – there is the smell of ozone, there is a process of ozonation.

But the ozone molecule, it has a relatively small resistance and eventually decomposes by modifying a more stable molecule is usually oxygen (02) – is the process of recombination of oxygen in the “neutral” state.

Therefore, when there is sunlight illumination air, the ozone occurs, and when no light for a long time, the ozone disappears gradually.

Ozone layer

As such, the “ozone layer” in the atmosphere does not exist, it is present in very small amounts in the whole layer of air, but with the height of the amount of the Earth is growing and reaching a maximum (in tenths of a percent) at high altitude (tens of kilometers), then decreases, with the maximum height is not constant (20-40 km), and that’s called the ozone layer high “ozone layer”.

In the absence of light the solar atmosphere of the polar regions of the planet during the polar night, when these areas are in the shadow of the Earth (alternately, over the north and south poles), respectively atmosphere for a long time not covered by solar rays and ozone decreases sharply, which is called “ozone holes “.

Ozone, although its content in the atmosphere is negligible (tenths and hundredths of a percent), plays a very important role in the atmosphere to preserve the bio-life on Earth because it has an important property – detain rigid cosmic radiation (cosmic rays) coming from the Sun as and from the Galaxy, adverse to all life on Earth.

Therefore, the ozone layer and is like a natural “shield” that protects the nature of death (for such a shield astronauts are suits and body of the spacecraft). Therefore, the places where the ozone becomes too small, called “ozone holes” and in these places the Earth appears overestimated the amount of hard cosmic radiation, which is unfavorable for all living things!

Therefore, during the polar nights appearance ozone holes – quite a natural phenomenon of nature, and accordingly, these conditions are considered to be very unfavorable. But then, when the polar night passes, starts atmosphere lighting sunlight, the amount of ozone and the ozone hole recovers disappear.

Ozone layer

Atmospheric ozone. Ozone layer

Meteorologists and Geophysics determine the content of ozone in the atmosphere using a special radiosondes and missile lifted into the atmosphere.

But unfortunately, except for the natural process of a temporary reduction in ozone caused by seasonal changes in light conditions, human activities interfere with this process and it is proved that the whole content of ozone in the atmosphere is reduced because of the appearance of gases such as CFCs (used in spray, Hairspray, refrigerators, etc.); these gases as they exit the atmosphere rise up (they are lighter than air) and the impact on the acceleration of the process of recombination – the amount of ozone begins to decrease, and the emerging “ozone hole” and become more and more slowly, decrease.

Therefore, there is an international program to fight for the preservation of the ozone layer from human impact and to prevent ingress of CFCs into the atmosphere and out of Freon in the respective devices and appliances.

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