The Oxygen-Ozone Screen

As you saw in Ghapter 6, our Sun bombards Earth with electromagnetic radiation, of which about 53% is infrared (IR) radiation, about 39% is visible radiation, and about 8% is ultraviolet (UV) radiation. IR radiation is the lowest in energy of these three, and ultraviolet radiation is the highest in energy. We have focused on the effect that these forms of radiation can have upon reaching Earth and have briefly mentioned that some of this electromagnetic radiation never reaches Earth because it is either absorbed or reflected. 

Ultraviolet radiation has wavelengths in the 200-400 nm range. This energy is sufficient to break some chemical bonds and to create havoc with many biological systems. Fortunately for us, much of the UV radiation that streams from the Sun towards Earth never reaches Earth. It is absorbed primarily by two important screening molecules, oxygen and ozone. Let s examine how this happens. 

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We will look at the importance of the oxygen-ozone screen as a mechanism for protecting us from dangerous UV radiation in Chapter 7. 

The Chapman cycle is a series of chemical reactions related to the oxygen-ozone screening... 

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