Aerosol Particle Effects on Warm and Cold Cloud Formation

所有的云滴和许多冰晶都是在大气中的悬浮粒子上形成的。这个实验室调查将研究这些“成核”过程的关键方面。这项研究强调有机物质（包括纯有机物种和土壤中的有机物质）和矿物粉尘的成核特性，因为它们以前没有被广泛研究过，而且越来越多的证据表明它们在大气中的重要性。将进行三种不同的实验室测量：亚饱和条件下颗粒的吸水量，作为云凝结核（CCN）的颗粒的活性，以及纯溶液液滴或由未溶解颗粒引起的冰核。将收集来自沙漠沙尘主要来源地区的土壤样本，并重新悬浮起来进行这些分析。需要检验的一个关键假设是，来自世界不同干旱地区的尘埃特征具有相似的特征，因此可以用共同的参数化来表示。该项目的其他目标将是检查已知混合成分的颗粒，并开发和测试结果的参数表示。预期的结果是对大气气溶胶的一些关键成分的成核特性进行新的表征，并开发新的方法来表示这些特征，这些特征可用于这些过程的天气和气候模式。这有可能影响未来的降水预报和气候模式中云的重要辐射特性的表示。

All cloud droplets and many ice crystals form on suspended particles in the atmosphere. This laboratory investigation will study key aspects of these "nucleation" processes. The study emphasizes the nucleating properties of organic material (including pure organic species and the organic material in soils) and mineral dust because they have not been studied extensively before and there is an increasing body of evidence that points to their importance in the atmosphere. Three different kinds of laboratory measurement will be made: water uptake on particles in subsaturated conditions, activity of particles as cloud-condensation nuclei (CCN), and ice nucleation of pure solution droplets or caused by undissolved particles. Samples of soil from regions that are significant sources of desert dust will be collected and re-suspended for these analyses. A key hypothesis to be tested is that the characteristics of dust from different arid regions of the world have similar characteristics and so might be represented by common parameterizations. Other objectives of this project will be to examine particles of known mixed composition and to develop and test parametric representations of the results. The expected result is new characterization of the nucleating properties of some key constituents of the atmospheric aerosol and the development of new ways of representing those characteristics that can be used in weather and climate models of those processes. This has potential to influence future forecasts of precipitation and representations of the important radiative properties of clouds in climate models.