UV Light, CFCs, and the Ozone Layer

Name: _________________________________       Date: _____________

High up in Earth's atmosphere, a protective layer of ozone gas shields Earth's inhabitants from the Sun's harmful ultraviolet or UV rays. But in recent decades, scientists have seen an alarming thinning of this ozone layer, particularly in the skies above Antarctica.

What is causing this "hole" in the ozone? What is being done about it? You'll find out in this activity.

1. You'll begin by finding out about ultraviolet rays. Go to Thinning Ozone Layer: More UV Coming to Earth and click the middle box labeled UV. Where do UV rays come from?
   
   
   
   
2. Why are these rays harmful?
   
   
   
   
3. What stops UV rays from getting to Earth's surface?
   
   
   
   
4. Next, click the link for ozone at the bottom of the UV page. What have scientists observed about the ozone layer?
   
   
   
   
5. What are CFCs and how do they get into the atmosphere?
   
   
   
   
6. What is the effect of CFCs on ozone?
   
   
   
   
7. What are countries doing about CFCs?
   
   
   
   
8. Next, click the link trouble at the bottom of the ozone page. How do UV-B rays, the most dangerous kind of UV rays, affect frogs and their eggs?
   
   
   
   
9. Now take the Ozone Hole Tour to learn about the Ozone Loss Over Antarctica. Scroll to TOMS Satellite Measurement and click for the movie of ozone levels from 1978–1992. (Be patient while the movie loads!) Blue and purple show low ozone levels. Click frame by frame then describe how ozone levels over Antarctica changed from 1978 to 1992.
   
   
   
   
10. Go to The Science of the Ozone Hole page. Scroll to the illustration below the heading Chemical Processes Leading to Polar Ozone Depletion. Complete this description of how ozone breaks down:
    
    
    Factories and homes spew out __________________.
    
    ______________________ breaks down CFCs in the ________________________.
    
    Breakdown products destroy __________________.
    
    
    
11. Finally, take a look at how ozone levels look today at Total Ozone Mapping Spectrometer (TOMS) site. Click each of the three images for North Pole, South Pole, and Global to enlarge them. What is today's ozone level range (difference between minimum and maximum) in each view?
    
    1. North Pole
       
       
       
       
    2. South Pole
       
       
       
       
    3. Global View