Atmosphere:
The atmosphere is a
very thin layer of air and moisture around the Earth.
The
atmosphere itself is not physically uniform but has significant variations in
temperature and pressure with altitude, which define a number of atmospheric
layers. These include:
1.
Troposphere: (0 to 16 km) is closest to Earth’s surface.
It contains 78% Nitrogen, 21% Oxygen, small amounts of gases like Argon, Carbon
dioxide and most of the atmosphere’s moisture and plays a vital role in our
weather system.
2. Stratosphere: (16 to 50 km) is
dry and contains higher concentration of Ozone than any other layer.
3. Mesosphere (50 to 80km) has
similar composition with the exception of moisture and ozone. Here, the density
and temperature of these gases are very low
4. Thermosphere (80 to 640km) is
made up of two layers, one is Ionosphere where high-energy electromagnetic waves
from Sun are absorbed causing particles to become electrically charged ions.
The other outer layer is Exosphere containing very few particles mainly
Hydrogen.
The boundaries between these four layers are defined by
abrupt changes in temperature, and are as follows:
1. Tropopause,
2. Stratopause
3. Mesopause.
Ozone (O3),
or trioxygen, is a triatomic molecule, consisting
of three oxygen atoms. The
highest levels of ozone in the atmosphere are in the stratosphere, in
a region also known as the ozone.
Ozone Depletion in the Stratosphere
Ozone
depletion takes place when more ozone is destroyed than produced leading to an
overall destruction of stratospheric ozone. Ozone loss can occur naturally for
a shorter period of time but chlorine and bromine released from man-made synthetic
compounds are now considered and acknowledged
as the main cause of Ozone depletion.
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