Ice Particle Development in orographic wave clouds: Results from the Ice In Clouds Experiment

During the Ice in Clouds Experiment (ICE) Layer (L) Clouds, lenticular wave clouds were profiled along or against wind direction and from top to bottom and spanning a temperature range of about -10 to -38C on nine days. Particle size distributions and 2D particle images were obtained with a suite of four conventional and open path small particle probes, sizing particles with diameters <50 microns, and four probes sizing above this range. Total condensed and liquid water contents were measured. Radar reflectivities were measured above and below the aircraft and lidar observations above the aircraft.

Our talk will summarize observations from ICE-L. It will include a characterization of the ice concentrations as a function of distance downwind of the leading edges of the clouds and the temperature. Measured ice particle sizes will be compared to those calculated from a simple kinematic model and classical growth rate calculations. Anomalous observations of unexpectedly high ice concentrations will be reported and explained. Characteristics of the ice particles-their shapes, cross-sectional areas and densities are derived for these ideal growth conditions at water-saturated conditions. We will discuss/comment on the likely ice nucleation mechanisms for these clouds.