E-Mail IMAGE: Clouds cool the climate system by reflecting incident sunlight. The reflection of sunlight and cooling is stronger in the presence of pollution particles. Pollution also affects the development of clouds: While... view more Credit: Glassmeier et al The impact of atmospheric aerosols on clouds and climate may be different than previously thought. That is the conclusion of cloud researcher Franziska Glassmeier from TU Delft. The results of her study will be published in Science on Friday, January 29th. Clouds Cloud decks cover vast stretches of the subtropical oceans. They cool our planet because they reflect incoming sunlight back to space. Air pollution in the form of aerosols -- particles suspended in the atmosphere -- can increase this cooling effect because it makes clouds brighter. The cooling effect of pollution offsets part of the warming effect of greenhouse gases. How much exactly, is one of the largest uncertainties faced by climate scientists.