The absorption of solar radiation by ozone is probably one of the most widely known process occurring in the stratosphere. Ozone is naturally formed there through photochemical reactions involving the oxygen molecules of the air and the ultraviolet incoming solar radiation. The latter is thus prevented from reaching the Earth's surface and having harmful consequences on life. Furthermore, the production of ozone in the stratosphere is a source of heat in this region and acts as controlling the vertical thermal structure of the atmosphere. Temperature indeed increases with altitude between 10 and 50 km, maintaining the stratosphere as a stable region from the dynamical point of view. Other stratospheric gases, such as carbon dioxide, water vapour and methane (known as "greenhouse gases", as is ozone) determine significant radiative forcing terms. By modulating the amount of energy available in the troposphere (the region comprised between the surface and 10 km altitude), they also act as controlling the circulation there. Conversely, wave processes (most of them originating from the lowest part of the atmosphere, play a crucial role in driving the circulation in the stratosphere.

A number of changes and events have been observed in the stratosphere in the past 30 years: changes in ozone, aerosols from two major volcanic eruptions perturbing the chemical and radiative budgets, water vapour and temperature data that indicate various changes, variations in stratospheric circulation, and climate changes in the Arctic and Antarctic stratospheres especially during the winter-spring seasons. All of them indicating that the stratosphere-troposphere system is changing due to both natural and anthropogenic factors.