Abstract:
Clouds play an important role in determining the amount of sunlight that reaches earth's surface or is reflected back to the universe. Thereby, they are of great importance to the earth's heat balance by having a cooling effect on Earth's climate. Scientist have increasing evidence that aerosols, in particular bioaerosols such as bacteria, strongly affect the properties of clouds. Nevertheless, we lack detailed knowledge of their fundamental role in clouds. E.g. several studies showed that bioaerosols affect the lifetime of clouds and promote ice formation, that is central for rain formation, between 0 ° C and -15 ° C. Mineral particles, the majority fraction of aerosols, promotes ice formation only between -15 ° C and -40 ° C. However, to nail down the impact of bioaerosols once for all we need direct measurements of their metabolic activity and of their quantitative role in ice formation. DRAMA will close these gaps of knowledge by determining the metabolic activity of microbes and their capacity to form ice under atmospheric conditions. Ultimately, DRAMA will provide data that will significantly improve weather and climate models of the future.