MCQ Detailed View

Ozone (O₃) in the atmosphere is formed mainly in the stratosphere by the action of solar radiation on oxygen molecules (O₂). The process begins when ultraviolet (UV) radiation from the Sun strikes oxygen molecules. This high-energy radiation splits O₂ into individual oxygen atoms, a process called photodissociation. These free oxygen atoms then react with other O₂ molecules to form ozone (O₃).

The efficiency of this process depends strongly on the flux of UV radiation. Visible radiation and infrared radiation do not have enough energy to break the oxygen–oxygen bond. Gamma rays have extremely high energy but they are not abundant in the atmosphere and are not the controlling factor for ozone production. Only UV radiation, particularly in the UV-C range (wavelengths below 240 nm), has the right amount of energy to split O₂ molecules efficiently.

Ozone formation and destruction together form what is called the Chapman cycle, which explains how ozone is continuously created and broken down in the stratosphere. Ozone absorbs UV-B and UV-C radiation, protecting living organisms on Earth from harmful radiation. Without this ozone shield, life on land would be exposed to damaging ultraviolet rays, leading to health and environmental problems.

The balance between ozone formation and destruction is sensitive to atmospheric conditions. Human activities, such as the release of chlorofluorocarbons (CFCs), disturb this balance by accelerating ozone destruction. However, the initial creation of ozone always depends on the availability of ultraviolet radiation.

Therefore, the rate of ozone formation in the atmosphere is controlled by the flux of ultraviolet radiation, which provides the necessary energy for splitting oxygen molecules and starting the ozone formation cycle.