Atmospheric brown clouds are atmospheric accumulations of carbonaceous aerosol particles spanning vast areas of the globe. They have recently gained much attention, from the scientific community and from the general population, as they severely impact several aspects of everyday life. Aside from affecting regional air quality and negatively impacting human health, these clouds affect biogeochemical cycles and profoundly influence the radiation budget of the Earth, resulting in severe climatic and economic consequences. Carbonaceous aerosol particles are generated primarily by combustion processes, including biomass and fossil fuel burning. Natural emissions and transformations of volatile organic species in the atmosphere also contribute to the development of atmospheric brown clouds.