Investigation of Cloud Entrainment Using a Laboratory Heated-Jet Analogue

摘要/Prasad，9714810 在真实的云层中进行良好的观测是困难的。 最好的情况是，利用飞机、气球和雷达，研究人员能够在特定的时刻得到一些在有限的区域内发生的事情的“快照”，但是这样做是非常昂贵和困难的。 因此，我们对云过程的了解非常有限。 对真实的云进行良好观测的困难使得许多研究人员试图通过在实验室模拟中使用液体来研究云过程的类似物来理解云过程。 尽管由于液体和空气之间的差异（例如，液体通常实际上是不可压缩的），这种方法存在一些固有的问题，但是仍然存在许多问题可以以这种方式有效地解决。 其中之一是环境干燥空气夹带到云中的问题。 该奖项支持使用实验室模拟浮力发展云来解决夹带问题的研究。 云凝结释放潜热的模拟方法是通过在流体流中加热金属丝，以欧姆方式注入热量。 流场将使用一些最新的先进技术进行可视化，包括激光诱导荧光，粒子图像测速和粒子图像测温。 计划中的研究预计将提供有关夹带的新的和新鲜的见解，并导致云的数值模型中的浮力对流和夹带的特性的改进。

Abstract/Prasad, 9714810 It is difficult to make good observations in real clouds. At best, using aircraft, balloons, and radar, researchers have been able to get a few "snapshots" of what is going on in a limited region of a aq few clouds at particular instants, but to do so is very costly and difficult. Thus our knowledge of cloud processes is very spotty and limited. The difficulty of getting good observations of real clouds has led a number of investigators to try to get at an understanding of cloud processes by studying analogs of cloud processes in laboratory simulations using liquids. Although there are some problems inherent in this approach because of differences between liquids and air (liquids are generally virtually incompressible, for example), there are still many questions that may be addressed usefully in this way. One of these is the question of entrainment of environmental dry air into clouds. This award supports research using a laboratory analog of a buoyant developing cloud to address the problem of entrainment. The release of latent heat in a cloud by condensation will be simulated by injecting heat ohmically, that is, through heated wires in the fluid flow. The flow fields will be visualized using some of the most recent advanced techniques, including Laser Induced Fluorescence, Particle Image Velocimetry, and Particle Image Thermometry. The planned research is expected to provide new and fresh insights about entrainment, and to lead to improvements in the characterization of buoyant convection and entrainment in numerical models of clouds.