Rosenfeld Daniel, Lohmann Ulrike, Raga Graciela B, O'Dowd Colin D, Kulmala Markku, Fuzzi Sandro, Reissell Anni, Andreae Meinrat O
Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Science. 2008 Sep 5;321(5894):1309-13. doi: 10.1126/science.1160606.
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.
气溶胶作为云凝结核（CCN），因此对云的特性和降水的起始有重大影响。据报道，大量人为气溶胶因其辐射和CCN活动，既会减少降雨，也会增加降雨。在一个极端情况下，CCN浓度低的原始热带云降雨过快，无法成熟为长寿云。另一方面，污染严重的云在降水能够发生之前就蒸发掉了大量水分，如果考虑到气溶胶霾层导致的地表加热减少，它们根本就无法形成。我们提出了一个概念模型来解释这种明显的二分法。
