Scaling of cloud microphysical properties in a convection-cloud chamber

Scaling of cloud microphysical properties in a convection--cloud chamber is explored using theoretical and computational models. The fidelity of the models is evaluated using observations of cloud liquid water content versus aerosol injection rate, performed in the Pi Chamber. The models and experiments are based on steady injection of aerosol particles that are activated to form cloud droplets, balanced by the removal of cloud droplets through sedimentation. Limits of fast and slow microphysics, compared to the turbulent mixing time scale, are explored. Measured liquid water contents in the Pi convection-cloud chamber agree, to within the measurement uncertainty, with the predicted power-law scaling with cloud droplet concentration. Expressions for the scaling of microphysical properties with chamber depth are obtained. Finally, required conditions for onset of droplet growth by collisions are explored using the models.