Turbulence Intermittency for Cloud Physics (TITCHY)

云物理的湍流间歇性 (TITCHY)

• 批准号: EP/Z000149/1
• 负责人: Oliver Buxton
• 金额: $ 221.74万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FZ000149%2F1
• 关键词: Turbulence; Intermittency; Cloud; Physics; TITCHY

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.

自从人类诞生以来，人们就仰望天空，也许每天都会把图像投射到积云产生的各种令人眼花缭乱的形状上，并问道：“为什么云会形成然后消失？”“和“为什么下雨？“直到今天，这些问题仍然没有答案，尽管我们对云的物理学的理解已经取得了巨大的进步。有人问：“我们能理解没有湍流的云吗？”我的回答是“不！“云是通过夹带环境空气穿过云的清晰可见的边界而生长的。同样，它们通过降水而衰减，更重要的是，空气的流失回到环境中。这两个过程都没有得到很好的理解。近年来，我已经开始研究两个相邻湍流区域之间的夹带，或湍流/湍流夹带（TTE），这正是湍流大气边界层中暖积云发生的情况。卷吸稀释了云，并从根本上改变了它的微观物理，但云的TTE还没有被理解，部分原因是它固有的不稳定性。如果不了解水团、能量、动量、浮力和热量进入云的TTE，就不可能将其参数化，从而改善天气/气候预报。TITCHY将通过精心设计的最先进的实验和模拟活动来做到这一点，这些实验和模拟专门用于评估我的TTE范式对云微物理学的重要性。TITCHY的第二个目标是研究云中水滴的物理学;特别是作用于它们的力，以及它们如何影响最终产生雨滴的碰撞/聚结过程。这些力量受到间歇性湍流物理迄今被忽视，但潜在的至关重要的。基于我的变革性新思想，TITCHY试图以现代的观点解决一个百年老问题。