title: Flood or drought: how do aerosols affect precipitation?
abstract: Aerosols serve as cloud condensation nuclei (CCN) and thus have a substantial effect on cloud properties and the initiation of precipitation. Large concentrations of human-made aerosols have been reported to both decrease and increase rainfall as a result of their radiative and CCN activities. At one extreme, pristine tropical clouds with low CCN concentrations rain out too quickly to mature into long-lived clouds. On the other hand, heavily polluted clouds evaporate much of their water before precipitation can occur, if they can form at all given the reduced surface heating resulting from the aerosol haze layer. We propose a conceptual model that explains this apparent dichotomy.
authors.affiliation: Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel. daniel.rosenfeld@huji.ac.il
authors.forename: Daniel
authors.initials: D
authors.lastname: Rosenfeld
authors.forename: Ulrike
authors.initials: U
authors.lastname: Lohmann
authors.forename: Graciela B
authors.initials: GB
authors.lastname: Raga
authors.forename: Colin D
authors.initials: CD
authors.lastname: O'Dowd
authors.forename: Markku
authors.initials: M
authors.lastname: Kulmala
authors.forename: Sandro
authors.initials: S
authors.lastname: Fuzzi
authors.forename: Anni
authors.initials: A
authors.lastname: Reissell
authors.forename: Meinrat O
authors.initials: MO
authors.lastname: Andreae