Photochemical reactions play a major role in atmospheric chemistry because sunlight drives many chemical processes in the air. These reactions affect air quality, climate, and life on Earth.
Contributions of Photochemical Reactions in Atmospheric Chemistry
- Formation of Ozone (O₃) in the Stratosphere
- Sunlight splits oxygen molecules (O₂) into oxygen atoms.
- These atoms combine with O₂ to form ozone.
- Importance: Protects life by absorbing harmful UV radiation.
- Photochemical Smog in the Troposphere
- Sunlight reacts with nitrogen oxides (NOₓ) and volatile organic compounds (VOCs).
- Produces ozone, PAN, aldehydes → causes smog, health issues, and reduced visibility.
- Breakdown of Pollutants
- Sunlight can trigger reactions that decompose harmful gases, such as NO₂, CO, or hydrocarbons.
- Helps in natural cleaning of the atmosphere, though sometimes secondary pollutants form.
- Greenhouse Gas Chemistry
- Photochemical reactions influence gases like methane and ozone, which affect global warming and climate change.
- Aerosol and Radical Formation
- Sunlight produces free radicals (like OH•) through photochemical reactions.
- These radicals react with pollutants, affecting air quality and chemical cycles.
In short: Photochemical reactions in the atmosphere control ozone formation, pollution levels, radical chemistry, and climate, making sunlight-driven chemistry a key factor in Earth’s environment.