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#### Ozone: The Chapman-Cycle

Ozone is created and destroyed in the stratosphere.  The English mathematician and geophysisist, Sidney Chapman, investigated and described this cycle. Because of his work, the cycle is called the "Chapman-Cycle".

The flash animation below shows the Chapman-Cycle and all the important steps in it.

Symbols:

- Oxygen atom

- Oxygen molecule

- ozone

- photons of high, but different, energies (ultra-violet radiation)

- heavy weight particles with different temperatures

1. Symbols used in animation.
© 2003 Seesing, Tausch, Universität-Duisburg-Essen, Duisburg

Exercise 1

Add the missing words to the text. The missing words are:

ozone molecule ; ozone molecules; cracking of ozone; oxygen atom ; oxygen atom; oxygen atoms; oxygen atoms; oxygen molecule ; oxygen molecule; oxygen molecule; oxygen molecules; UV-light ; UV-light; energy; energy; wavelength

1. High-energy (short wave) UV-light can crack (breakdown)  ________________________ into ________________________.

2. If an ________________________, an ________________________ and a heavy weight particle impact in a "triple collision" an ________________________ is formed. The heavy weight particle can be a dust particle, or another big gas molecule such as nitrogen gas.

3. The heavy weight particle absorbs the  ________________________, which becomes free during ozone formation. It delivers the ________________________slowly to the environment afterwards.

4.  ________________________ can be broken down similarly by _______________________. The ________________________needed by this do not need to have as much energy as they do to breakdown oxygen molecules into oxygen atoms. The ________________________can be larger. The products of this ______________________ are an ______________________ and an_______________________.

5.  When two ________________________collide, an ________________________is formed.

2. Animation in steps.
© 2003 Seesing, Tausch, Universität-Duisburg-Essen, Duisburg

Exercise 2

Explain briefly which form of energy in the stratosphere is converted into warmth by the Chapman-Cycle.