Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

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Environmental Impact
1. The exosphere
(2400km))
The sunlight still contains very high-energy photons, which can heat gas
particles in the exosphere up to 2,500 degrees C during the day.
2. The ionosphere Most high energy photons are absorbed here leading to a few air
molecules becoming electrically charged.
3. The ozone layer This thin layer at the top of the stratosphere absorbs most of the ultraviolet
(UV) light. Too much UV light can cause damage to living things
so the ozone layer is very important in protecting life on Earth.
4.The stratosphere
(50km)
5. The troposphere (8-15
km).
6. Absorption of
radiation emitted by the
Earth
Ozone depletion relies on the clouds in the stratosphere: Polar
stratospheric clouds (PSCs), also known as nacreous clouds, are
CLOUDS in the winter polar STRATOSPHERE at altitudes of 15,000–25,000
metres (50,000–80,000 ft). They are implicated in the formation of OZONE
HOLES; [1] their effects on ozone depletion arise because they support
chemical reactions.
The troposphere contains most of the air molecules, nearly all the water
vapour so all of the clouds are in this layer. All these particles mean that
a lot of sunlight is scattered. Shorter wavelengths (violet and blue) are
scattered more than longer wavelengths, making the sky appear blue.
The Earth emits a lot of long wavelength radiation from its surface and
much of this is absorbed and scattered in the troposphere. Greenhouse
gases such as carbon dioxide and water vapour are responsible for
most of this absorption, making the temperature around the Earth
higher.
This ozone filter efficiently screens out almost
all the harmful ultraviolet rays of the sun; the
ozone layer absorbs most of the dangerous
UV-B radiation (radiation between UV-A which
is allowed through and UV-C which is mainly
captured by oxygen, as indicated in Figure
1.2). Any damage that is done to the ozone
layer will lead to increased UV-B radiation.
Increases of UV-B radiation have been clearly
observed in areas experiencing periods of
intense ozone depletion.
Any increased UV-B that reaches the earth’s
surface has a potential to cause considerable
harm to the environment and to life on earth.
A small decrease in the ozone layer could
significantly increase the incidence of skin
cancer, and could lead to an acceleration
of the rarer but more virulent form of
cancer known as coetaneous malignant
melanoma. Increased UV-B could lead to
increased incidents of eye damage, including
cataracts, deformation of the eye lenses, and
presbyopia. Eye cataracts, the leading cause
of blindness in the world, are expected to
increase considerably.
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