# Generating a stratocumulus-like cloud top in a convection-cloud chamber

## TL;DR

This paper shows how a convection-cloud chamber can simulate stratocumulus cloud tops, helping improve understanding of cloud behavior and climate impacts.

## Contribution

The study demonstrates a novel method to replicate stratocumulus cloud tops in a lab using controlled wall conditions.

## Key findings

- A steady-state cloud top can be formed by cooling lower sidewalls and warming the bottom surface.
- A temperature inversion at the cloud top is achieved by warming upper sidewalls and the top surface.
- The turbulent kinetic energy profile matches that of a convective boundary layer.

## Abstract

Entrainment plays a critical role in determining the lifetime and precipitation of stratocumulus clouds, which, in turn, influence regional weather patterns and earth energy balance. Despite its importance, cloud-top entrainment remains a significant source of uncertainty, particularly in coarse-resolution atmospheric models. To date, no laboratory facility has been developed to experimentally study cloud-top entrainment, but a future convection-cloud chamber could provide this unique capability. Using numerical simulations, we demonstrate how a stratocumulus-like cloud top can be replicated through the precise control of wall conditions in a cloud chamber. Additionally, we explore potential experiments and their expected outcomes. Our findings strongly support the development of such a facility and highlight its potential benefits.

Stratocumulus-topped boundary layers play a crucial role in influencing daily weather and earth energy balance. Entrainment at the stratocumulus cloud top affects the cloud’s lifetime, precipitation, and radiative properties, but our understanding remains limited due to the lack of resolution in both field observations and numerical simulations. A recently proposed convection-cloud chamber with detailed control of sidewall temperatures can provide a unique opportunity to explore this mechanism in a laboratory setting. In this work, we use numerical simulations to demonstrate that this design can produce a cloud top that mimics the entrainment interfacial layer in a stratocumulus cloud. Our results show that a steady-state cloud can be formed by cooling the lower portions of the sidewalls and warming the bottom surface, while a temperature inversion at the cloud top can be generated by keeping the upper sidewalls and top surface warmer than the bottom. The turbulent kinetic energy profile and budget are similar to those found in a convective boundary layer, and inhomogeneous mixing near the cloud top can be observed. These findings significantly enhance the scientific value of constructing the tall convection-cloud chamber.