Unraveling the impact of turbulence in Mixed-phase Clouds

Introduction

Mixed-phase clouds—atmospheric complex three-phase systems containing suspended ice particles, supercooled water droplets, and water vapor—are responsible for most of the precipitations reaching the Earth’s surface. In addition, these clouds play a primary role in the planet’s radiative energy budget and the water cycle.

Research Gaps

Despite their relevance, there is a lack of a basic understanding of the complex hydrodynamics, heat, and mass transfer between the different water components with numerous scientific open questions. In the last decades, many scientific works have shown a significant impact of turbulence in “warm” (ice-free) clouds and “warm” rain formation in enhancing condensation/evaporation of rain droplets and promoting collisions.

Turbulence in Mixed-Phase Clouds

On the other hand, the role of turbulence in mixed-phase clouds has never been properly quantified; consequently, up to now, this topic has been nearly exclusively a subject pertaining to atmospheric physics rather than fluid dynamics. I want to change this perspective and analyze the rich dynamics of mixed-phase clouds using a combination of theoretical and numerical tools developed for general multiphase flows.

Project Objectives

MixClouds is a multidisciplinary project aiming to:

1. Understand the impact of turbulence in mixed-phase cloud microphysics of water hydrometeors.
2. Quantify this impact by determining typical ice and water droplet size distributions at given temperature, humidity, and turbulence levels.
3. Develop the next generation of numerical tools to couple multiphase turbulent dynamics at different scales.
4. Develop novel sub-grid models to parametrize mixed-phase cloud microphysics and test against known atmospheric observations.

Potential Impact

The final results can potentially generate a ground-breaking impact not only in the areas of turbulent multiphase flows and cloud physics but also in climatology and in all environmental and industrial applications involving suspensions of three-phase flows in the presence of phase changes.