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；以及对卷云结冰过程的模拟。将使用两种互补的方法：在科罗拉多州立大学的云室进行实验室实验，以及用数值云模型进行模拟。实验将模拟各种定义明确的云条件下的冰形成过程，相当于大气云。测量天然冰核是该设备的一项新应用；这项工作将建立一个大型膨胀室测量天然冰核的效用。将模拟卷云中均匀和非均匀冻结过程中的冰核过程。实验室实验将用于推导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，并对模型进行修正以提高其预测能力。冬季地形云播种的几个案例研究将使用新的成核公式进行动态微物理模型模拟。//

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. //