1. Ozone Depletion

2. All of the gases that surround Earth
What is the Atmosphere?
All of the gases that surround Earth
Mixture of mostly nitrogen and oxygen
Other gases that are present in trace
amounts include argon, carbon dioxide,
methane and water vapor

3. Composition of the Atmosphere
Nitrogen 78%
Oxygen 21%
Other 1%
Argon,
Carbon Dioxide
Methane
Water Vapor

4. The Composition of Gases in the Atmosphere is constantly changing!
Think of any examples of gases being added or
removed in the atmosphere

6. What Else is in the Atmosphere?
In addition to gases, the atmosphere also contains some particulates. We call these particles atmospheric dust.
What are some materials that might be part of atmospheric dust?

7. Atmosphere also contains particulates
Particulates – aka atmospheric dust
Includes:
Pollen
Volcanic ash, smoke and ash from fires
Bacteria
Soil particles
Aerosols

8. The force that pulls everything to the earth!
Gravity
The force that pulls everything to the earth!
Gravity causes the Earths atmosphere to be MORE dense near the Earth’s surface! So at higher elevations, the air becomes LESS dense!

9. Think… Denver, CO is a mile high city
Think… Denver, CO is a mile high city. If you were to ski in the Denver area, you might have a hard time breathing. Why?

10. Denver, CO is a mile high city
Denver, CO is a mile high city. If you were to ski in the Denver area, you might have a hard time breathing because… 1. You’re exercising and need more oxygen 2. However, the air is less dense which means it has less oxygen!

11. Think… Why do planes fly at higher altitudes where the air is less dense?

12. Planes fly at higher altitudes where the air is less dense because… At higher altitudes, the air is less dense, so there is less drag and therefore higher fuel efficiency.

13. How does gravity affect the layering of the atmosphere?
Denser materials are closer to the earth.
Denser layers of the atmosphere will be closer
to the earth.

14. Layers of the atmosphere?

15. Troposphere Nearest Earth’s surface About 18 km high Densest layer
Within this layer temperature decreases as altitude increases

16. Stratosphere Above Troposphere 18 km to 50 km Contains ozone layer
Ozone* molecules absorb UV energy from the sun and heat up this layer
Therefore, temperature Increases as altitude increases
*Ozone O3 reduce UV radiation that reaches the Earth

17. Mesosphere Above the Stratosphere 50 km to 80 km high Coldest layer
Temperature decreases as altitude increases

18. Thermosphere Farthest from Earths surface 80km-550 km
N2 and O2 absorb solar radiation
Temperatures of 2000 C
Molecules in this layer absorb harmful x-rays and gamma rays from the sun, causing atoms to become electrically charged ions
Also called the ionization layer
Aurora borealis- Solar lights

19. Review – layers of atmosphere
Troposphere – layer closest to surface; gas particles most dense here
Stratosphere – OZONE LAYER HERE!
Mesosphere – less dense that stratosphere – coldest layer
Thermosphere – farthest from surface; least dense and hottest; absorbs x-rays and gamma rays from sun

20. What happens to temp in each layer?
Troposphere – as alt increases, temp decreases
Stratosphere – as alt increases, temp increases
mesosphere – as alt increases, temp decreases
Thermosphere – as alt increases, temp increases

21. Activity Directions:
Watch the video clip of the atmosphere at one of the computers. (link on my teacher page)
Complete the 2 worksheets- colored pencils up front
When you have finished, take an article to read
Return to your seat and read the article

24. Interpret this Graph What happens as to the temperature as
you rise through the…
-Troposphere?
-Stratosphere?
-Mesosphere?
-Thermosphere?

25. What layer includes the Ozone layer?
 The Stratosphere
Ozone* is a molecule made of three oxygen atoms it can be found near the ground where its bad, or up in atmosphere where its good…hence, good up high, bad nearby
*Ozone O3 reduce UV radiation that reaches the Earth

26. What does the ozone layer do?
The ozone layer absorbs UV radiation from the Sun.
UV radiation is part of the electromagnetic spectrum.
Exposure to UV radiation can lead to skin cancer

27. So…Why is a hole in the ozone layer or ozone depletion bad???
Too much UV
radiation might
cause skin cancers

28. What is the ozone layer and where is it found?
The ozone layer is the layer of the atmosphere at an altitude of 15 to 40 km
Located in the stratosphere

29. What is the function of the ozone layer?
In the stratosphere, ozone absorbs ultraviolet solar radiation.
What is Ozone?
Ozone is a molecule made of three oxygen atoms

30. ozone Ozone in the Troposphere Ozone in the Stratosphere
Ozone is good up high, bad nearby!
It forms the ozone layer, which protects us from harmful UV radiation
In the troposphere, it is a pollutant, formed by the reaction of NOx, and VOCs with sunlight
Ozone is bad nearby, but good up high

31. So…What’s the issue with the ozone layer?
These satellite images below show the growth of the ozone hole (blue, then purple, then red) over the past two decades.

32. Chloroflouorocarbons (CFC’s)
How is ozone depleted?
Chloroflouorocarbons (CFC’s)
Chlorofluorocarbons (CFCs) are hydrocarbons in which some or all of the hydrogen atoms are replaced by chlorine and fluorine.
They are used in coolants for refrigerators and air conditioners and in cleaning solvents. They were also used as a propellant in spray cans of everyday products such as deodorants, insecticides, and paint.
Their use is now restricted because they destroy ozone molecules in the stratosphere

33. The chemical reaction that destroys ozone.

34. Chemical equation for this process…
CFCl3 + UV Light  CFCl2 + Cl Cl + O3  ClO + O2 ClO + O  Cl + O2
The free chlorine atom is then free to attack another ozone molecule
Cl + O3  ClO + O2 ClO + O  Cl + O2
and again ...
and again... for thousands of times
In this way, a chlorine atoms act as a catalyst.

35. How Does the Ozone Hole Form?
During the dark polar winter, strong circulating winds over Antarctica, called the polar vortex, separate cold air from surrounding warmer air.
The air within the vortex grows extremely cold.
Polar stratospheric clouds form at altitudes of about 21,000 m during the Arctic and Antarctic winter or early spring, when air temperatures drop below –80°C.
On the surfaces of polar stratospheric clouds, the products of CFCs are converted to molecular chlorine.
When sunlight returns to the South Pole in the spring, molecular chlorine is split into two chlorine atoms by UV radiation.
The chlorine atoms rapidly destroy ozone.
The destruction of ozone causes a thin spot, or ozone hole, which lasts for several months.

36. If ozone is also being produced as air pollution, why does this ozone not repair the ozone hole in the stratosphere?
Ozone is very chemically reactive. It can chemically burn your lungs (Good up high…bad near by)
Ozone produced by pollution breaks down or combines with other substances in the troposphere long before it can reach the stratosphere to replace ozone that is being destroyed

38. Why is a hole in the ozone a problem?
As the amount of ozone in the stratosphere decreases, more UV light is able to pass through the atmosphere and reach Earth’s surface.
UV light is dangerous to living things because it damages DNA.
Exposure to UV light makes the body more susceptible to skin cancer, and may cause other damaging effects to the human body.

39. What are the effects of thinning ozone layer on humans?
As the amount of ozone decreases, more UV light is able to pass through the atmosphere and reach Earth’s surface.
UV light damages DNA
Exposure to UV light makes the body more susceptible to skin cancer, and may cause other damaging effects to the human body.

40. Effects of ozone thinning on animals and plants
High levels of UV light can kill single-celled organisms called phytoplankton that live near the surface of the ocean  disrupt ocean food chains and reduce fish harvests
Decrease in phytoplankton could cause an increase in the amount of carbon dioxide in the atmosphere.
UV light could be especially damaging for amphibians, such as toads, because they lay eggs that lack shells in the shallow water of ponds and streams. UV light at natural levels kills many eggs of some species by damaging unprotected DNA.
UV light can damage plants by interfering with photosynthesis. This damage can lower crop yields

46. What have we done to protect the ozone layer?
1987
Montreal
group of nations made an agreement, called the Montreal Protocol, to sharply limit their production of CFCs.
1992
Copenhagen
_ At a second conference in Copenhagen, Denmark in 1992, developed countries agreed to eliminate most CFCs by 1995

48. 2007 was the 20th anniversary of the Montreal Protocol:
"The Montreal Protocol has been a resounding success," said Richard Stolarski, a speaker at the symposium from NASA's Goddard Space Flight Center, Greenbelt, Md. "The effect can be seen in the leveling off of chlorine compounds in the atmosphere and the beginning of their decline."
Since the Montreal Protocol was signed on Sept. 16, 1987, more than 100 nations have agreed to limit the production and release of compounds, notably human-produced chlorofluorocarbons, known as CFCs. CFCs and a list of other compounds are known to degrade the layer of ozone in the stratosphere that shields life from the sun's ultraviolet radiation. That process gives rise to the ozone hole above Antarctica.

49. Other forms of Pollution….
NOISE!!!
A sound of any kind is called a noise.
Some noises are unnecessary and can cause noise pollution.
Health problems that can be caused by noise pollution include loss of hearing, high blood pressure, and stress.
Noise can also cause loss of sleep, which may lead decreased productivity at work and in the classroom.

51. Other forms of Pollution….
LIGHT!!!!!
Light pollution does not present a direct hazard to human health, but it does negatively affect our environment.
The use of inefficient lighting in urban areas is diminishing our view of the night sky.
In urban areas, the sky is often much brighter than the natural sky.

53. Describe in 1 sentence what is happening in the diagram below.

54. Describe in 1 sentence what is happening in the diagram below.
The hole in the ozone has grown significantly over the past two decades over the continent of Antarctica

55. What causes ozone depletion?
A - Acid Rain
B - Volatile Organic Compounds
C - Chloroflourocarbons
D - Thermal Inversion

56. What causes ozone depletion?
A - Acid Rain
B - Volatile Organic Compounds
C - Chloroflourocarbons
D - Thermal Inversion

57. What happens to chlorine after it breaks down one molecule of ozone?
A – It moves on to break down another molecule of ozone
B – It creates acid rain
C – It destroys aquatic ecosystems
D – It disappears

58. What happens to chlorine after it breaks down one molecules of ozone?
A – It move on to break down another molecule of ozone
B – It creates acid rain
C – It destroys aquatic ecosystems
D – It disappears

59. What does “good up high – bad near by” mean?

60. What does “good up high – bad near by” mean?
Ozone in the stratosphere is helpful because it protects us from harmful UV radiation
Ozone on the ground level is toxic to humans and breaks down before reaching the stratosphere – so it can’t be used to replace the missing ozone

61. What are some effects of ozone depletion on people?

62. What are some effects of ozone depletion on people?
UV rays can cause genetic damage that can lead to skin cancer or other health problems

63. What have we done about the hole in the ozone layer?
A - We are moving ground level ozone into the stratosphere
B - CFC’s were no longer produced and later banned from use
C – We are cleaning up the CFC’s from the atmosphere over Antarctica
D - Nothing

64. What have we done about the hole in the ozone layer?
A - We are moving ground level ozone into the stratosphere
B - CFC’s were no longer produced and later banned from use
C – We are cleaning up the CFC’s from the atmosphere over Antarctica
D - Nothing