When ultraviolet (UV) light strikes the ozone layer, a series of photochemical reactions occur. The ozone layer, predominantly located in the stratosphere, consists of ozone (O₃) molecules that play a critical role in absorbing harmful UV radiation from the sun, particularly UV-B and UV-C rays.
Here's what happens during this interaction:
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Absorption of UV Radiation: Ozone molecules absorb UV radiation, which prevents a significant portion of harmful UV rays from reaching the Earth's surface. When ozone absorbs UV light, the energy from the radiation breaks the bonds within the ozone molecules.
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Dissociation: The absorbed energy causes ozone (O₃) to dissociate into diatomic oxygen (O₂) and a free oxygen atom (O). This reaction can be represented by the equation: \[ O_3 + UV \rightarrow O_2 + O \]
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Formation of Ozone: The free oxygen atom can recombine with other O₂ molecules in the atmosphere to form ozone again, helping to sustain the ozone layer. This can occur through a reaction like: \[ O + O_2 \rightarrow O_3 \] However, this balance can be disrupted by various factors, including pollutants like chlorofluorocarbons (CFCs).
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Energy Regulation: The process of converting UV energy into heat through these reactions also helps to regulate the temperature of the stratosphere.
In essence, the ozone layer serves as a protective shield that absorbs and converts UV radiation, thereby preventing these dangerous rays from directly impacting the Earth's surface and causing harm to living organisms, such as skin damage and increased risk of skin cancer in humans, as well as detrimental effects on ecosystems.