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• The atmosphere is divided into five layers. It
is thickest near the surface and thins out with
height until it eventually merges with space.
• 1) The troposphere is the first layer above the
surface and contains half of the Earth's
atmosphere. Weather occurs in this layer.
• 2) Many jet aircrafts fly in the stratosphere
because it is very stable. Also, the ozone
layer absorbs harmful rays from the Sun.
• 3) Meteors or rock fragments burn up in the
mesosphere.
LAYERS OF THE
ATMOSPHERE
2
• 4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits.
• 5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.
Ozone
layer
3
Ozone is…
Ozone is a form of oxygen with 3 oxygen atoms (O3).
The oxygen we breath
has 2 atoms of oxygen
(O2).
Ozone is…
• Ozone is highly
corrosive and toxic
and is used as a
disinfectant.
• It can be found in
small concentrations in
the troposphere where
it is considered a
pollutant.
Ozone…
• Ozone is very highly reactive and
will combine with other
substances easily.
• Near the earth's surface, these
reactions cause rubber to crack
and damage people's lung
tissues.
• Inhaling ozone can damage the
respiratory tract, which enables
us to breathe.
What is the ozone layer?
Most of the planet’s
ozone hangs out in
the Stratosphere,
the layer above the
Troposphere.
What is the ozone layer?
• Ozone in the stratosphere protects people,
animals, and plants from harmful ultraviolet rays.
• The ozone layer is a layer of gas consisting
of O3 molecules, called ozone, that forms
when free Oxygen molecules bond to O2
molecules.
So, why is the ozone layer
important to life on Earth?
• The stratospheric ozone
layer completely stops the
penetration of UV-C rays
and eliminates most of the
UV-B rays.
• Therefore, the ozone layer
protects life on Earth from
the harmful effects of
solar radiation on a daily
basis.
What’s Eating the Ozone?
• Scientists in the 1960s realized that something was going wrong in the ozone layer.
• They soon figured out that human actions were damaging Earth's shield against harmful radiation.
• Ozone in the troposphere is produced when sunlight and heat react with
nitrous oxides and volatile organic compounds, known as ozone precursors.
• These pollutants are emitted by vehicles, power plants, refineries, and
chemical plants.
• The amounts of “good” and “bad” ozone in the atmosphere depend on a
balance between processes that create and destroy ozone; an upset in this
balance has serious consequences for life on Earth.
Source: EPA
What is the Ozone Hole?
The ozone hole is not
technically a “hole” where no
ozone is present, but is actually a
region of depleted ozone in
the stratosphere over the Antarctic
that happens at the beginning of
Southern Hemisphere spring
(August-October).
The average concentration of
ozone in the atmosphere is about
300 Dobson Units; any area
where the concentration drops
below 220 Dobson Units is
considered part of the ozone hole.
Who discovered the Ozone Hole?
The Antarctic Ozone Hole was discovered in 1985 by British scientists Joseph Farman, Brian Gardiner, and Jonathan Shanklin of the British Antarctic Survey.
The Ozone Hole has steadily grown in size (up to 27 million sq. km.) and length of existence (from August through early December) over the past two decades.
What causes Ozone Depletion?
• The Ozone Hole is caused by chemicals called CFCs, short for chlorofluorocarbons. CFCs escape into the atmosphere from refrigeration and propellant devices and processes, and they are so stable they last for decades. This long life allows some CFCs to eventually reach the stratosphere.
• The chemicals that make up CFCs, mainly chlorine and fluorine, float around the stratosphere, breaking up ozone molecules.
• One molecule of CFC can destroy more than 100,000 molecules of stratospheric ozone.
• Today, no spray cans contain CFCs. Other chemicals are gradually replacing the CFCs in air conditioners.
Ultraviolet Radiation
The depletion of the ozone layer leads to higher levels of
ultraviolet radiation reaching Earth's surface.
This in turn can lead to a
greater incidence of skin cancer, cataracts, and impaired immune systems, and is expected also to reduce crop yields, diminish the productivity of the oceans, and possibly to contribute to the decline of amphibians that is occurring around the world.
What is the Montreal Protocol?
• The Montreal Protocol is a landmark international agreement designed to protect the stratospheric ozone layer.
• The Montreal Protocol says that the production and consumption of compounds that deplete ozone in the stratosphere--chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2030.
What can we do, as concerned citizens, to
ensure that our children have a viable planet
to inhabit?
Create reliable models To gain a better understanding of the effects ozone
depletion has on organisms living within different
ecosystems
Enforcement of Montreal Protocol To reduce concentrations of chemicals responsible for
ozone depletion
Monitoring chemicals being emitted
Gain a better overall understanding on just how
ozone depletion is affecting our planet
25
What can we do?
• Make sure that technicians working on your car air
conditioner, home air conditioner, or refrigerator
are certified by an EPA approved program to
recover the refrigerant (this is required by law).
• Have your car and home air conditioner units and
refrigerator checked for leaks. When possible,
repair leaky air conditioning units before refilling
them.
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What can we do?
• Contact local authorities to properly dispose of
refrigeration or air conditioning equipment.
• Protect yourself against sunburn. Minimize sun
exposure during midday hours (10 am to 4 pm).
Wear sunglasses, a hat with a wide brim, and
protective clothing with a tight weave. Use a
broad spectrum sunscreen with a sun protection
factor (SPF) of at least 15 and 30 is better.
EGEE 102 - Pisupati 28
What can We do?
• Keep your automobile well tuned and maintained.
• Carpool, use mass transit, walk, bicycle, and/or
reduce driving, especially on hot summer days.
• Be careful not to spill gasoline when filling up
your car or gasoline-powered lawn and garden
equipment. During the summer, fill your gas tank
during the cooler evening hours.
29
What can we do?
• Make sure your car's tires are properly inflated and
your wheels are aligned.
• Participate in your local utility's energy
conservation programs.
• Seal containers of household cleaners, workshop
chemicals and solvents, and garden chemicals to
prevent VOC from evaporating into the air.
Dispose of them properly.