The stratosphere is the atmospheric layer comprised between 8–18 km for its lower altitudes and 40–60 km for its upper altitudes, which correspond more or less to the stratospheric ozone layer thickness. In this part of the atmosphere, intense UV radiations from the sun fuel an active and energetic photochemical reactor leading to the formation of two important by-products: the ozone molecule (O₃), an oxygen allotrope, and heat that mostly originates from absorption of UV radiation by ozone. While heat causes a strong vertical stability of the air mass in the stratosphere (stratified atmosphere), large concentrations of ozone form a UV-protective shield allowing the development of life on the Earth’s surface. The intense UV radiations combined with the ozone concentration generate a distinct stratospheric chemistry where nitrogen, oxygen, and halogen compounds are highly coupled in cycles that maintain the chemical stability of this UV-protective atmospheric layer