Investigation of Cloud Entrainment Using a Laboratory Heated-Jet Analogue

点击翻译按钮获取中文摘要

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.