1. 13-2 The Ozone Shield
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2. A. Chemicals that Cause Ozone Depletion
1. The ozone layer is an area in the stratosphere where ozone is highly concentrated.

3. A. Chemicals that Cause Ozone Depletion
2. Ozone is a molecule made of 3 oxygen atoms (O3) and absorbs ultraviolet (UV) rays that can harm living cells.

4. A. Chemicals that Cause Ozone Depletion
3. Human-made chemicals called chloroflurorocarbons (CFC’s) are damaging the ozone layer.

5. A. Chemicals that Cause Ozone Depletion
4. CFC’s are inexpensive to make and used in items such as coolants, paint, and deodorant.

6. A. Chemicals that Cause Ozone Depletion
5. On the earths surface, CFC’s are stable. In the atmosphere CFC’s break apart.

7. A. Chemicals that Cause Ozone Depletion
6. The chlorine atoms from CFC’s breakdown ozone in the stratosphere.

8. A. Chemicals that Cause Ozone Depletion
7. Estimates show that 1 chlorine atom can break down up to 100,000 ozone molecules.

9. B. The Ozone Hole
1. A thinning of stratospheric ozone that occurs over the poles during the spring.

10. B. The Ozone Hole
2. In 1985, scientists in Antarctica found the ozone layer over the south pole was thinned by 50-90%.

11. B. The Ozone Hole
3. Scientists and governments have been working together world wide and the ozone in the stratosphere has stopped declining.

12. C. How Does the Ozone Hole Form?
1. During the dark polar winter, winds over Antarctica (called the polar vortex), isolate cold air from warm air.

13. C. How Does the Ozone Hole Form?
2. When air in the vortex falls below -80°C clouds made of water and nitric acid, called polar stratospheric clouds, start to form.

14. C. How Does the Ozone Hole Form?
3. CFC’s enter the clouds and are broken down into chlorine atoms that combine with UV rays and for ozone holes that last several months.

15. D. Effects of Ozone on Living Things
1. ↓Ozone= ↑ UV Radiation
2. 2. UV damages DNA, which can lead to skin cancer.

16. D. Effects of Ozone on Living Things
3. UV kills phytoplankton which disrupts aquatic food chains and increases CO2 in the atmosphere.

17. D. Effects of Ozone on Living Things
4. UV interferes with photosynthesis, damaging plant life.

18. E. Protecting the Ozone Layer
: Group of nations met in Canada and formed the Montreal Protocol to limit production of CFC’s.

19. E. Protecting the Ozone Layer
2. A 2010 study showed that many ozone-depleting Substances (ODS) have been phased out.

20. E. Protecting the Ozone Layer
3. Scientists are still searching for ways to protect the ozone layer because CFC’s may remain active in the atmosphere for years.