Ozone. Computer artwork of oxygen (O) atoms combining with oxygen (O2) molecules to form ozone (O3) molecules in the atmosphere above the Earth. Ozone is an allotrope of oxygen that is produced in the stratosphere by the action of high-energy ultraviolet (UV) radiation on oxygen (O2). It forms a stable layer, known as the ozone layer, which screens the Earth from harmful UV radiation. When the O3 molecules absorb low energy UV radiation in the ozone layer it breaks the atomic bonds releasing an oxygen atom, but the atom quickly recombines with another O2 molecule to regenerate O3.