A Laboratory and Field Study of the Radiative and Electrical Properties of Ice in the Atmosphere

冰晶的实验室研究将包括它们的辐射特性，特别是热红外(2-18米)的消光和发射率。这将包括由局部电场定向的晶体。通过多次路径遍历将获得足够的消光以进行测量。发射率将通过与云层温度上下的背景进行比较来获得。光学深度测量将在685 nm处进行，以便为归一化红外消光和吸收光学厚度测量提供综合云投影面积的方便测量。消光测量将考虑比以前产生的云的尺寸和习性光谱更窄的云，利用La Mer发生器的原理(在特定温度下控制成核，然后控制增长)。液滴成核模式将控制结晶度(每核的晶体数量)，这将与CCN的性质(尺寸、组成)有关。作为这项研究的补充，将研究在卷云温度下，微量杂质缺陷在导致冰晶习性变化中的作用。实验将在现有的扩散室内进行，并将用于改进成核研究中的晶体生产方案。这将产生与不同温度下生长的晶体(薄板、纯柱、中空柱、等轴晶体和杂质(HNO3))相关的特定晶体形状。这些研究将通过在几个项目(TOGA-COARE、EUCREX、FIRE II WISP)中已经在高层飞行中获取的数据与大气进行比较，这些项目在已知条件下收集了晶体。这将与它们的成核特性(颗粒挥发性和热分馏)Cn和物理尺寸与临界过饱和度以及由此而来的晶体浓度和形态有关。实验室生产的冰云消光和发射的灵敏度将与晶体的习性和大小有关，并用作发展数值/分析模式的基准。来自这些不同方法的想法将被综合起来，以了解卷云的形成及其可能的辐射特性。热带卷云起源于深对流和相关的电活动。这种冰和电活动的来源(作为高空和低层地面降水的替代冰)将根据已经获得的关于开普敦的NOAA P3、几次飓风和热带对流的数据进行调查。这将把冰的演化机制与较低云层的合并过程、过渡区二次冰产生的速度以及最终可能的冰水物质进入砧座的流量联系起来，从而在高空提供不同的辐射特性。

Hallett/Abstract A laboratory study of ice crystals will include their radiative properties, especially thermal infra-red (2-18 m) extinction and emissivity. This will include crystals oriented by local electric fields. Sufficient extinction for measurement will be obtained by multiple path traverses. The emissivity will be obtained by comparison with backgrounds above and below cloud temperature. Optical depth measurements are to be performed at 685 nm to provide a convenient measure of integrated cloud projected area for normalizing infrared extinction and absorption optical depth measurements. The extinction measurements will consider clouds with narrower size and habit spectra than previously produced, utilizing the principle of the La Mer generator (controlled nucleation followed by controlled growth) at a specific temperature. The liquid drop nucleation mode will control the crystallinity (number of crystals per nucleus), which will be related to CCN properties (size, composition). Complementary to this study, an investigation will be made of the role of trace impurity defects role in leading to ice crystal habit changes at cirrus temperatures. Experiments will be carried out in an existing diffusion chamber and will be used to refine the protocol for crystal production in the nucleation study. This will give rise to specific crystal shapes associated with crystals growing at different temperature (thin plate, pristine column, hollow columns, equiaxed crystals and impurity (HNO3). These studies will be compared with the atmosphere through data already taken in high level flights in several projects (TOGA-COARE, EUCREX, FIRE II WISP) where crystals have been collected under known conditions. These will be related to their nucleation characterization (particle volatility and thermal fractionation) CN and physical size vs. critical supersaturation and thence to crystal concentration and morphology. The sensitivity of the laboratory prod uced ice cloud extinction and emission will be related to crystal habit and size and used as benchmarks for development of a numerical/analytical model. The ideas from these different approaches will be synthesized in understanding cirrus formation and its likely radiative properties. Tropical cirrus originates in deep convection with associated electrical activity. The origin of such ice and electrical activity (as a surrogate for ice production aloft and lower level surface precipitation) will be investigated from data already obtained on the NOAA P3 in CAPE, several hurricanes and tropical convection. This will relate ice evolution mechanisms to coalescence processes at lower cloud levels, the rapidity of secondary ice production in the transition region and ultimately the likely flux of ice water substance into the anvil to give differing radiative properties aloft.