3. Ozone Layer
A layer in Earth's atmosphere which
contains relatively high concentrations
of ozone (O3).
Absorbs 97–99% of the sun's high
frequency ultraviolet light, which is
potentially damaging to life on earth.
4. Ozone Layer (cont’d)
It is mainly located in the lower portion of
the stratosphere from approximately
13 km to 20 km above Earth, though the
thickness varies seasonally and
geographically.
5. Ozone Layer (cont’d)
The ozone layer was discovered in 1913 by
the French physicists Charles
Fabry and Henri Buisson.
Its properties were explored in detail by the
British meteorologist G. M. B. Dobson, who
developed a simple spectrophotometer (the
Dobson meter) that could be used to measure
stratospheric ozone from the ground.
6. Ozone Layer (cont’d)
Between 1928 and 1958 Dobson
established a worldwide network of ozone
monitoring stations which continues to
operate today.
The "Dobson unit", a convenient measure
of the columnar density of ozone
overhead, is named in his honour.
7. Origin of Ozone
The photochemical mechanisms that give
rise to the ozone layer were discovered by
the British physicist Sidney Chapman in
1930.
9. Ultraviolet Light and Ozone
The ozone is vitally important because it
absorbs the biologically harmful UV
radiation coming from the sun.
UV radiation is divided into 3 categories
UV-A (400–315 nm)
UV-B (315–280 nm)
UV-C (280–100 nm)
10. Ozone Depletion
The ozone layer can be depleted by free radical
catalysts, including nitric oxide (NO), nitrous
oxide (N2O), hydroxyl (OH), atomic chlorine (Cl),
and atomic bromine (Br).
The concentrations of chlorine and bromine
have increased markedly in recent years due to
the release of large quantities of man-
made organohalogen compounds,
especially chlorofluorocarbons (CFCs)
and bromofluorocarbons.
