Laboratory and Numerical Model Studies of Ice Formation in Clouds

这项工作涉及云中冰形成的三个方面：碘化银冰成核气溶胶的影响；天然冰核的测量；以及卷云中冰形成的模拟。将使用两种互补的方法：在CSU的云室中进行实验室实验，以及使用数值云模型进行模拟。这些实验将模拟各种定义明确的云条件下的结冰过程，相当于大气云。测量天然冰核是该设备的一个新应用；这项工作将建立一个大型膨胀室来测量天然冰核的效用。卷云中的冰成核过程将被模拟为均匀和非均匀冻结过程。实验室实验将被用来推导出冰成核的功能定量描述。实验室结果将与模型的结果进行比较，并将对模型进行修订，以提高其预测能力。利用新的形核公式，用动力微物理模式模拟了几个冬季地形云播撒的个例。//

This work addresses three aspects of ice formation in clouds: the effects of silver iodide ice nucleating aerosols; measurements of natural ice nuclei; and simulations of ice formation in cirrus clouds. Two complementary approaches will be used: laboratory experiments in CSU's cloud chambers, and simulations with numerical cloud models. The experiments will simulate ice forming processes in a variety of well-defined cloud conditions, equivalent to atmospheric clouds. Measuring natural ice nuclei is a new application of the facilities; this work will establish the utility of a large expansion chamber to make measurements of natural ice nuclei. Ice nucleation processes in cirrus clouds will be simulated for both homogeneous and heterogeneous freezing processes. The laboratory experiments will be used to derive functional quantitative descriptions of ice nucleation. The laboratory results will be compare with those of the models, and revisions to the models will be made to improve their predictive capabilities. Several case studies of winter orographic cloud seeding will be simulated with a dynamical microphysical model using the new nucleation formulations. //