Virtual Clouds: investigating and modelling warm cloud microphysics using multiscale numerical techniques

Research Project, 2023 – 2026

A cloud is a complex object made of liquid droplets, solid particulate, and various gases suspended in the atmosphere. Clouds influence Earth ́s climate by absorbing or reflecting the solar radiation and increasing precipitation in certain regions. The current weather/climate predictions need accurate models of clouds that are considered the larger uncertainty source. Climate change is a socio-economic challenge, and climate simulations are the only scientific tool to predict future scenarios. A significant amount of this uncertainty is given by turbulence affecting the cloud microphysics by entrainment, stirring, and mixing, resulting in strong fluctuations and intermittency in temperature, humidity, and aerosol concentration. Moreover, turbulence is considered a key factor in rain formation. The air fluctuations activate the first nuclei of rain droplets, accelerate the condensation process and promote collisions between droplets. However, quantifying the impact of turbulence in cloud microphysics is still a challenge. This project will improve our knowledge of the microphysical processes in warm clouds (i.e. ice free) using novel numerical simulations across many relevant scales. In addition, we will derive new stochastic models for droplet size distributions and implement them in an existing LES atmospheric solver. To fulfill the project goals, we will combine our expertise in different disciplines: fluid mechanics, atmospheric physics, and statistical physics.