Turbulence Intermittency for Cloud Physics (TITCHY)

自从人类诞生以来，人们就抬头仰望天空，也许每天都会把图像投射到积云产生的令人眼花缭乱的各种形状中，并问道：为什么云形成后又消失了？和“为什么要下雨？”到今天为止，这些问题仍然没有得到回答，尽管我们对云的物理的理解当然已经有了很大的进步。有人挑衅地问道：“我们能在没有湍流的情况下理解云吗？”对此，我的回答是响亮的“不！”云是通过将环境空气带过云的清晰可见边界而增长的。同样，它们通过降水，更重要的是将空气带回环境中而腐烂。这两个过程都没有得到很好的理解。近年来，我开始研究两个相邻湍流区域之间的夹卷，或湍流/湍流夹带(TTE)，这正是大气边界层中温暖的积云发生的情况。卷吸作用稀释了云，并从根本上改变了它的微观物理，然而，人们对云的TTE并不了解，部分原因是它固有的间歇性。如果不了解将水质量、能量、动量、浮力和热量转化为云的TTE，就不可能将其参数化，从而改善天气/气候预报。蒂奇将通过精心组织的最先进的实验和模拟活动来做到这一点，这些实验和模拟是专门为评估我的TTE范例对云微物理的重要性而设计的。Tichy的第二个主题是研究云中水滴的物理；特别是作用在水滴上的力，以及它们如何影响最终产生雨滴的碰撞/合并过程。这些力受制于迄今被忽视但可能具有关键重要性的间歇性湍流物理。基于我的变革性新想法，Tichy试图用现代观点解决一个数百年来的问题。

Since the dawn of humankind people have looked up at the sky, perhaps projected every day images into the dazzling variety of shapes that cumulus clouds produce, and asked "why do clouds form and then disappear?" and "why does it rain?" To this day these questions remain unanswered, although of course our understanding of the physics of clouds has advanced enormously. It has been provocatively asked "can we understand clouds without turbulence?" to which my response is a resounding "no!" Clouds grow by entraining environmental air across the sharply defined visible boundary of the cloud. Similarly they decay through precipitation, and more importantly the detrainment of air back to the environment. Neither of these processes are well understood. In recent years I have jump started the field of entrainment between two adjacent regions of turbulence, or turbulent/turbulent entrainment (TTE) which is precisely the scenario that occurs for a warm cumulus cloud in the turbulent atmospheric boundary layer. Entrainment dilutes a cloud and fundamentally alters its microphysics, yet TTE for a cloud is not understood in part because of its inherent intermittency. Without understanding the TTE of water mass, energy, momentum, buoyancy, and heat into a cloud it is not possible to parameterise it and thereby improve weather/climate forecasts. TITCHY will do this, through a carefully co-articulated campaign of state-of-the-art experiments and simulations specifically devised to assess the importance of my TTE paradigm to cloud microphysics. The second thrust of TITCHY is to examine the physics of water droplets within a cloud; in particular the forces that act on them and how they affect the collision/coalescence process that ultimately yields raindrops. These forces are subject to intermittent turbulent physics hitherto neglected but potentially of critical importance. Based on my transformative new ideas, TITCHY seeks to tackle a centuries-old problem with a modern outlook.