Formation and Destruction of Ozone

The most energetic UV radiation (i.e., UV-C) canses Oj molecules in the stratosphere to dissociate  

The free oxygen atoms react with diatomic molecules of Oj to form ozone (Oj)  

The ozone molecules preferentially absorb UV-C with a wavelength of = 250 nm (Hartley absorption band) and are dissociated in the process  

When CFC gases are released into the atmosphere, they gradually rise into the lower stratosphere because they are not washed out of the troposphere by rain. In the stratosphere the chlorine atoms are released when the CFC molecules are broken up by energetic UV-C radiation as indicated by the reaction  

O3 + E — O2 + 0 (2.4) The chlorine permits reactions to occur that destroy  

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For the discussion of the formation and destruction of ozone in (In stratosphere it is convenient to define the photodissociation coefficient generally denoted by J (in units ofsec 1). J is the probability of dissocial mn of a molecule per second by light absorption. 

MFDO Modeling the formation and destruction of ozone by taking account of all flight corridors over the territory in question. 

The dominant loss of OH radicals is reaction with CO and organic compounds such as CH4, both reactions produce peroxy radicals. Peroxy radicals play a key role in atmospheric chemistry. They are intimately involved in the formation and destruction of ozone and in the photooxidation of all organic compounds in the atmosphere [4], The lifetime of OH radicals with respect to reactions Eq. 3 and Eq. 8 is of the order of a second and in the day-time a steady state condition is established. The OH radical concentration in the atmosphere varies with location, time of day, season, and meteo-... 

The next section presents the major photochemical processes affecting the formation and destruction of ozone in a pure oxygen atmosphere . 

The principal reactions in the photochemical process of formation and destruction of ozone are reactions (l)-(4), collectively known as the Chapman mechanisms... 

We see that different wavelength ranges are involved in formation and destruction of ozone. This corresponds to the different absorption spectra for molecular oxygen and ozone as it is shown in Figure 2. 

Chapman Cycle The set of four reactions that represents the steady-state formation and destruction of ozone in the stratosphere. 

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