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Bacteria in the atmosphere

 

Clouds determine the amount of sunlight that reaches earth's surface. Thereby, they are of great importance to the Earth's heat balance. Scientists have increasing evidence that aerosols, in particular bioaerosols like bacteria, strongly affect the properties of clouds. Nevertheless, we lack detailed knowledge of their fundamental role in clouds. For instance, several studies showed that bioaerosols affect cloud lifetime and promote ice formation, that is central for rain formation, between 0 °C and -15 °C. Mineral dust, the majority type of aerosols, promotes ice formation only between -15 and -40 °C. However, to nail down the impact of bioaerosols once for all, we need direct measurements of their activity and of their quantitative role in ice formation. The research project 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 contribute to improve the weather and climate models of the future.