<Dd> O 2 + u v l i g h t ⟶ 2 O (λ ≲ 200 nm) (\ displaystyle \ mathrm (O_ (2) + uv ~ light \ longrightarrow 2 ~ O) \ qquad (\ lambda \ lesssim 200 ~ (\ text (nm)))) </Dd> <Dd> O + O 2 ⟶ O 3 (\ displaystyle \ mathrm (O + O_ (2) \ longrightarrow O_ (3))) </Dd> <P> The ozone layer is extremely important to modern life as it absorbs harmful ultraviolet radiation: </P> <Dl> <Dd> O 3 + u v l i g h t ⟶ O 2 + O (λ ≲ 300 nm) (\ displaystyle \ mathrm (O_ (3) + uv ~ light \ longrightarrow O_ (2) + O) \ qquad (\ lambda \ lesssim 300 ~ (\ text (nm)))) </Dd> </Dl>

What are the two most important processes in the cycling of oxygen in and out of the atmosphere