A gaseous component of the atmosphere.
Ozone, the triatomic form of oxygen (O3), is a gaseous component of the atmosphere. In the troposphere, it forms both naturally and by photochemical reactions involving gases stemming from human activities (“smog”). Tropospheric ozone is a greenhouse gas. In the stratosphere, ozone is formed by the interplay of ultraviolet solar radiation and molecular oxygen (O2). Stratospheric ozone plays a pivotal part in the stratospheric radiation balance. Its highest concentration is in the ozone layer.