How did the ozone layer form?
The process, in proper terms is called ozone depletion.
At high altitudes, UV (ultra-violet light) would strike a chlorofluorocarbon (CFC) molecule, freeing a chlorine radical (Cl).
This chlorine radical would collide with an ozone (
When another oxygen radical strikes the formed molecule, which is a
That's how it works.
P.S. : For further reading, you might want to watch a video my classmates did at school:
It might be useful.......
The proposed mechanism by which ozone is created is usually called the "Chapman Mechanism'.
The Chapman mechanism was published around the 1930s. This mechanism came under scrutiny later in the twentieth century because of the growth of the hypothesis that chlorofluorocarbons react with ozone in the manner described, reducing the concentration of ozone at high level, a hypothesis that depended critically on the validity of the Chapman mechanism.
The main focus of the scrutiny is the absence of direct experimental evidence, but there is also a theoretical objection is that ultra-violet cannot break the covalent bond (at least not in the direct manner proposed by Chapman). Additionally at the very low pressures and temperatures there are other highly unstable loose structures of molecules that can form and have significant lifetimes and absorption properties.
The hypothesis that chlorofluorocarbons "destroy ozone molecules in the stratosphere" is still open to investigation, despite political decisions based on the assumption that it is true.