The stratosphere is the second layer of the atmosphere as we go upward. The troposphere, the lowest layer, is right below the stratosphere. The next higher layer above the stratosphere is the mesosphere. The stratosphere stretches between 15 and 50 kilometers up from the Earth's surface. read more
So the ozone layer is formed in the stratosphere, because that is where the solar radiation is attenuated enough to make ozone at the pressure there, and destroy ozone at a constant rate, that leaves a steady state level of ozone. Ozone made / drifting higher, is ripped to oxygen atoms quickly. read more
Ozone is unstable with respect to Oxygen and so water vapour at lower levels of atmosphere breaks down Ozone molecules. The stratosphere is very dry; air there contains little water vapor. That's why the Ozone layer stabilizes there. read more
The UV light that the ozone layer protects us from is a necessary component in the creation of ozone molecules. When UV rays strike an oxygen molecule, it breaks the oxygen down into two atoms of oxygen. read more