SGER: Origin and Consequences of 'Dry Lightning' in a Dry Desert Environment

智慧价值：高空雷暴(有时称为“干雷暴”)源于中层水汽的平流，云层凝结层接近0°C。湿层以下是干燥空气，因此任何降水，特别是以较小颗粒形式存在的降水，都很容易蒸发，无法到达地表。在局部地形和局部辐合效应的辅助下，潮湿地区的对流可能会发生电荷分离，导致对地面的撞击，并有能力在干燥的地表条件下引发火灾。这类事件与更深层次的不稳定雷暴形成对比，雷暴形成于潮湿的空气中，云底温度高于20摄氏度，不仅导致通过高空混合相区产生电荷，而且在地表引发显著降雨，阻止了在以前干燥的条件下发生任何火灾。首席调查员将与野火专家合作，对这些干燥雷暴的特征进行初步调查，这些雷暴似乎对一些野火的引发有重大影响。这项调查将包括确定可能导致电活性干雷暴形成的前置条件。更广泛的影响：这项研究的最终目的是汇集对预测和预报类似的未来情景很重要的事件的各个方面，并检查特定气象和中层云形成条件以及相关电荷产生的频率。该项目还有进一步的后果，因为火灾产生的大量烟雾可能会导致顺风向延伸数英里的健康问题。预测此类事件的能力可能会对公众健康产生影响，并可能对及早部署灭火能力产生影响。

Intellectual Merit: High level thunderstorms (sometimes called 'dry thunderstorms') originate from advection of mid level moisture with cloud condensation level near 0°C. Below the moist level lies dry air so that any precipitation particularly, in the form of smaller particles readily evaporates and fails to reach the surface. Charge separation may occur from convection in the moist region, aided by local orographic and local convergence effects, leading to strikes to ground, with the ability to initiate fires under the dry surface conditions. Such events are in contrast to deeper instability thunderstorms, formed in moist air and having cloud base temperatures above 20°C, leading not only to charge generation through the mixed phase regions aloft but giving rise to significant rain at the surface, discouraging any fire starts under the previously dry conditions. In collaboration with wildfire experts, the Principle Investigator will perform a preliminary investigation into the characteristics of these dry thunderstorms which appear to have a significant influence on the initiation of some wildfires. This investigation will include ascertaining the antecedent conditions that might lead to the formation of electrically active dry thunderstorms. Broader Impact: The ultimate purpose of the study is to assemble aspects of the events important for anticipating and forecasting similar future scenarios and to examine the frequency of the particular meteorological and midlevel cloud forming condition and the associated charge generation. There are further ramifications of the project since the large amount of smoke produced by the fires may lead to health problems extending many miles downwind. The ability to predict such events may have implications for public health as well implications for early deployment of fire fighting capabilities.