Editing Ozone–oxygen cycle (section)

===Below thermosphere: Reaction rates at steady state===
Odd oxygen species (atomic oxygen and ozone) have net creation rate only by oxygen dissociation (reaction 1), and net destruction by either ozone conversion or oxygen recombination (reactions 4 and 5). At steady state these processes are balanced, so the rates of these reactions obey:
:(rate of reaction 1) = (rate of reaction 4) + (rate of reaction 5).

At steady state, ozone creation is also balanced with its removal. so: 
:(rate of reaction 2) = (rate of reaction 3) + (rate of reaction 4).

It thus follows that:
:(rate of reaction 2) + (rate of reaction 5) = (rate of reaction 3) + (rate of reaction 1).
The right-hand side is the total photodissociation rate, of either oxygen or ozone.

Below the thermosphere, the atomic oxygen concentration is very low compared to molecular oxygen.<ref>Richter, H., Buchbender, C., Güsten, R., Higgins, R., Klein, B., Stutzki, J., ... & Hübers, H. W. (2021). Direct measurements of atomic oxygen in the mesosphere and lower thermosphere using terahertz heterodyne spectroscopy. Communications Earth & Environment, 2(1), 19.</ref> Therefore, oxygen atoms are much more likely to hit oxygen (diatomic) molecules than to hit other oxygen atoms, making oxygen recombination (reaction 5) far rarer than ozone creation (reaction 2). Following the steady-state relation between the reaction rates, we may therefore approximate:<ref>Hingane, L. S. (1984). Ozone in the mesosphere and lower thermosphere. Proceedings of the Indian Academy of Sciences-Earth and Planetary Sciences, 93, 91-103.</ref>
:(rate of reaction 2) = (rate of reaction 3) + (rate of reaction 1)