Broadening of drop-size spectra by ice crystal vapor growth
Authors
Jerry Y. Harrington — Pennsylvania State University
Zachary Lebo — California Institute of Technology
Kara Jo Sulia — University of Albany
Category
Cloud Properties
Description
Observations of ice and liquid within mixed-phase clouds sometimes show correlations between the existence of ice and larger drops. This observation has led to the speculation that ice crystal production may be explained by the existence of the larger drops. How nucleation occurs in mixed-phase clouds is a critical problem in understanding mixed-phase cloud evolution: observed clouds appear to be able to maintain larger ice precipitation rates and concentrations along with supercooled liquid water than models can predict. Nevertheless, we present theoretical and model simulations that suggest ice crystals can produce preferential regions of larger drops through the process of diffusional growth alone. This mechanism produces natural broadening of the drop-size spectrum as the smaller drops evaporate and the larger drops grow. We present cases that show that this effect is most strongly evident at lower ice concentrations and at particular temperatures.
