Luftchemie

Luftchemie, or atmospheric chemistry, is the study of chemical processes that determine the composition and transformations of gases, vapors, and aerosols in Earth's atmosphere. It encompasses the troposphere and the stratosphere and considers both natural emissions (plants, oceans, lightning) and human activities (fossil fuel combustion, industry, agriculture). The field seeks to understand how trace gases are produced, transformed, transported, and interact with radiation, clouds, and surfaces.

Key topics include photochemistry driven by sunlight, radical chemistry (OH, RO2, HO2), and the formation and loss of ozone. In the stratosphere, ozone shields the surface from ultraviolet radiation; in the troposphere, ozone is a pollutant and greenhouse gas formed from NOx and volatile organic compounds in sunlight. Oxidation of VOCs produces secondary organic aerosols; sulfur dioxide and nitrogen oxides form sulfate and nitrate aerosols. Water vapor, clouds, and aerosols influence reaction rates and climate forcing. The field also investigates deposition, heterogeneous chemistry on particle surfaces, and feedbacks with radiation and rainfall.

Methods include ground-based, airborne, and satellite measurements; laboratory experiments; and chemical transport modelling. Instruments range from gas chromatographs, mass spectrometers, and chemiluminescence detectors to infrared and ultraviolet spectrometers and LIDAR. Modelling approaches include box models, regional and global chemical transport models, and climate-chemistry models with data assimilation. Applications cover air quality management, climate research, ozone-layer monitoring, and the evaluation of environmental policies.