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UV radiation and ozone
Solar radiation is the radiation emitted by the sun. The electromagnetic spectrum of the sun has its highest intensity in the range of visible light.
Depending on its wavelength, solar radiation varies in terms of intensity and spectral distribution due to absorption and scattering while entering the earth’s atmosphere. In addition, the intensity of solar radiation reaching the earth’s surface, i.e. the "subaerial solar radiation", strongly depends on climatic conditions and solar altitude.
Solar UV radiation
The solar UV radiation is absorbed by ozone in the stratosphere and troposphere. This filter function heavily depends on the UV wavelength. UV radiation intensity at ground level decreases markedly with wavelengths below about 330 nanometres (nm). This phenomenon is also referred to as "UV-B border".
UV radiation with wavelengths below about 290 nm (UV-C) is not measurable any more in our latitudes even in summer. According to this, any change in the atmospheric ozone concentration will cause an alteration of the subaerial UV exposure.
Variations of ozone content
The total atmospheric ozone content in our latitudes is subject to natural season variations with a maximum in spring and a minimum in autumn.
During the last few years, however, extremely low levels have been recorded particularly in late winter/spring, also referred to as "mini holes in the ozone layer". This is primarily due to the inflow of ozone-depleted air from subtropical latitudes. In addition, the dispersal of the polar vertex in spring might cause a transfer of polar air with low ozone content to moderate latitudes.
Ozone concentration and UV radiation
As a result of decreasing ozone concentrations in the atmosphere there is an increase especially in the intensity of UV-B radiation, i.e. additional very high energy UV radiation is reaching the ground.
The biological effectiveness of this radiation component is very high, and even small variations of the ozone content in the stratosphere, therefore, substantially influence the danger potential of sunlight at the earth’s surface.
State of 2018.09.13