When UV radiations from the sun reaches earth’s atmosphere which is heavily rich in oxygen. Then these UV rays split molecular oxygen (O2-reactant) into free oxygen (O-Product). Afterwards, this free oxygen reacts with molecular oxygen; it forms ozone (O3-Finalproduct).
O2 \(\overset{UV}\longrightarrow\) O + O
O + O2 → O3 (Ozone)
