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

智力优点：高空雷暴（有时称为“干雷暴”）起源于接近0°C的云层凝结水平的中层水汽平流。在潮湿的水平面以下是干燥的空气，所以任何降水，特别是以较小颗粒的形式，都很容易蒸发，无法到达地面。在局部地形和局部辐合效应的帮助下，潮湿地区的对流可能发生电荷分离，导致撞击地面，并在干燥的表面条件下引发火灾。这样的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°C，不仅导致通过高空混合相区域产生电荷，而且在地面产生大量降雨，阻止任何火灾在先前干燥的条件下开始。首席调查员将与野火专家合作，对这些似乎对某些野火的发生有重大影响的干燥雷暴的特征进行初步调查。这项调查将包括确定可能导致电活动干雷暴形成的先决条件。更广泛的影响：这项研究的最终目的是收集事件的各个方面，以预测和预报类似的未来情景，并检查特定气象和中层云形成条件的频率以及相关的电荷产生。由于火灾产生的大量烟雾可能会导致健康问题，因此该项目还会产生进一步的后果。预测此类事件的能力可能对公共卫生产生影响，也可能对消防能力的早期部署产生影响。

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.