atoms. (Rowland 1989) The free oxygen atoms can then combine with oxygen molecules (O2) to form ozone (O3) molecules. O2 + UV light -* 2 O O + O2 + M -* O3 + M (where M indicates conservation of energy and momentum) The same characteristic of ozone that makes it so valuable, its ability to absorb a range of ultraviolet radiation, also causes its destruction. When an ozone molecule is exposed to ultraviolet energy it may break back into O2 and O. During dissociation the atomic and molecular oxygens gain kinetic energy, which produces heat and causes an increase in atmospheric temperature. (Rowland 1989)Ozone production is driven by UV radiation of wavelengths less than 240 nm. Ozone dissociation typically produces atomic oxygen that is stable when exposed to longer wavelengths, up to 320 nm, and shorter wavelengths of 400 to 700 nm. Longer wavelength photons penetrate deeper into the atmosphere, creating regions of ozone production and destruction. (Rowland 1989) When an ozone molecule absorbs even low energy ultraviolet, it splits into an ordinary oxygen molecule and a free oxygen atom. O3 + UV, visible light -* O + O2 The free oxygen atom may then combine with an oxygen molecule, creating another ozone molecule, or it may take an oxygen atom from an existing ozone molecule to create two ordinary oxygen molecules. (Rowland 1989)O + O2 -* O3 or O3 + O -* O2 + O2 Processes of ozone production and destruction, set off by ultraviolet radiation, are often referred to as "Chapman Reactions." Most O3 destruction takes place through catalytic processes rather than Chapman Reactions. Ozone is a highly unstable molecule that readily donates its extra oxygen molecule to free radical species such as nitrogen, hydrogen, bromine, and chlorine. (Rowland 1989) These compounds naturally occur in the stratosphere, released from sources such as soil, water vapor, and the oceans. O3 + X -* XO + O2 (where X may be O, NO, OH, Br or Cl) The Ozone BalanceOver...
