Answer:
The ozone layer in the stratosphere is formed and maintained through a delicate balance between the formation and dissociation of ozone. Ozone (O3) is formed naturally in the stratosphere when oxygen molecules (O2) are split apart by ultraviolet (UV) radiation from the sun, producing highly reactive oxygen atoms (O). These oxygen atoms then react with other oxygen molecules to form ozone:
O2 + UV radiation → O + O
O + O2 → O3
This process is known as the Chapman cycle.
On the other hand, ozone can also be dissociated by UV radiation, which breaks the ozone molecule apart into oxygen atoms and molecules:
O3 + UV radiation → O + O2
This process is known as photodissociation.
The balance between ozone formation and dissociation is crucial for maintaining the thickness of the ozone layer. If the rate of ozone formation exceeds the rate of dissociation, the ozone layer will thicken. Conversely, if the rate of dissociation exceeds the rate of formation, the ozone layer will thin.