This is a presentation regarding some of those little threats our Earth is going through....The presentation is made interesting with a wide range of pictures, illustrations and animations...Please download to see the animated slideshow...Hope this comes of help to you!

3. A molecule containing three atoms of
oxygen is called ozone. Ozone is very
rare in our atmosphere, averaging about
three molecules of ozone for every 10
million air molecules. In spite of this
small amount, ozone plays a vital role
in the atmosphere.

4. Ozone is mainly found in two regions of the
Earth's atmosphere. Most ozone (about 90%)
resides in a layer that begins between 6 and
10 miles (10 and 17 kilometers) above the
Earth's surface and extends up to about 30
miles (50 kilometers). This region of the
atmosphere is called the stratosphere. The ozone
in this region is commonly known as the
ozone layer.

6. Ozone present in the stratosphere plays a
beneficial role by absorbing most of the biologically
damaging ultraviolet sunlight. The absorption of
ultraviolet radiation by ozone creates a source of
heat. Ozone thus plays a key role in the
temperature structure of the Earth's atmosphere.
Without the filtering action of the ozone layer,
more of the Sun's UV radiation would penetrate the
atmosphere and would reach the Earth's surface.
Many experimental studies of plants and animals
and clinical studies of humans have shown the
harmful effects of excessive exposure to UV
radiation.

8. At the Earth's surface, ozone comes into
direct contact with life-forms and displays
its destructive side (hence, it is often called
"bad ozone"). Because ozone reacts strongly
with other molecules, high levels of ozone
are toxic to living systems. Several studies
have documented the harmful effects of
ozone on crop production, forest growth, and
human health. The substantial negative
effects of surface-level ozone present in the
troposphere from direct toxicity contrast
with the benefits of the additional filtering
of UV radiation that it provides.

9. There is also widespread scientific and
public interest and concern about losses of
ozone in the stratosphere. Ground-based
and satellite instruments have measured
decreases in the amount of stratospheric
ozone in our atmosphere. Over some parts of
Antarctica, up to 60% of the total overhead
amount of ozone (known as the column
ozone) is depleted during Antarctic spring
(September-November). This phenomenon
is known as the Antarctic ozone hole. In the
Arctic polar regions, similar processes occur
that have also led to the depletion of column
ozone.

11. The ozone hole is an annual thinning of
the ozone layer over Antarctica. The most
pronounced decrease in ozone has been in the
lower stratosphere. However, the ozone hole is
most usually measured not in terms of ozone
concentrations at these levels (which are
typically of a few parts per million) but by
reduction in the total column ozone.

12. The Antarctic Ozone
Hole

14. The Ozone hole as
seen from the Earth

15. The cause of the ozone holes is generally agreed to
be CFC (chlorofluorocarbon) compounds which
break down due to ultraviolet light and
become free radicals containing chlorine high in
the Earth's atmosphere. These radicals then break
down the ozone catalytically. The ozone layer can
also be depleted by free radical catalysts,
including nitric oxide (NO), nitrous
oxide (N2O), hydroxyl(OH), atomic chlorine (Cl),
and atomic bromine (Br).

17. A chlorofluorocarbon (CFC) is an organic
compound that contains only carbon, chlorine,
and fluorine, produced as a volatile derivative
of methane and ethane. Chlorofluorocarbons
(CFCs) are anthropogenic compounds that have
been released into the atmosphere since the 1930s
in various applications such as in airconditioning, refrigeration, blowing agents in
foams, insulations and packing materials,
propellants in aerosol cans, and as solvents.

19. Through an international agreement known
as the Montreal Protocol on Substances that
Deplete the Ozone Layer, governments have
decided to eventually discontinue production
of CFCs, halons, carbon tetrachloride, and
methyl chloroform (except for a few special
uses), and industry has developed more
"ozone-friendly" substitutes. All other things
being equal, and with adherence to the
international agreements, the ozone layer is
expected to recover over the next 50 years or so.

23. The greenhouse effect is the process in which
greenhouse gases absorbs radiation (the infra
red rays) and re- radiates it in all directions.
Since part of this re-radiation is back towards
the surface and the lower atmosphere, it results
in an elevation of the average surface
temperature above what it would be in the
absence of the gases.

28. CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
co2

29. A greenhouse is a structural building with
different types of covering materials, such as
a glass or plastic roof and frequently glass or
plastic walls; it heats up because incoming
visible sunshine is absorbed inside the
structure. Air warmed by the heat from
warmed interior surfaces is retained in the
building by the roof and wall; the air that is
warmed near the ground is prevented
from rising indefinitely and flowing away.
This process in which the heat is trapped
within the greenhouse can be compared to
the way in which the heat radiations are
trapped in the earth’s atmosphere.

30. Green house effect is something that cannot be prevented but can
be reduced. It can be reduced in the following ways:
1. By opting for greener technologies that are eco-friendly.
2. By reducing emissions from automobiles, the greenhouse gases
can be reduced.
3. By preventing deforestation, because plants absorb a great
amount of CO2 from the atmosphere.
4. By using CFC-free refrigerators.
5. By reducing use of aerosols because they produce CFCs.

31. Global warming refers to an unequivocal and
continuing rise in the average temperature of Earth's
climate system. Most of global warming is being
caused by increasing concentrations of greenhouse
gases produced by human activities. Future climate
change and associated impacts caused by global
warming will vary from region to region around the
globe. Global warming can be prevented by reducing
the emission of greenhouse gases.

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Increase in spread of disease.
Warmer waters and more hurricanes.
Increase in droughts and heat waves.
Economic consequences.
Melting of polar ice caps.
Floods.
Fires and wildfires.
Storms.
Death by smog.
Desertification.
Tsunamis.
Cold waves.
Increase in volcanic activities.
Loss of biodiversity and animal extinction.

33. Melting and breaking down of
polar ice caps.

34. Artist’s illusion of New York city
underwater.

35. Artist’s illusion of backwards
evolution in case of polar bears.