The Particle Imaging (PI) Nephalometer was used to take images and phase function measurements of laboratory grown cloud particles. Phase function measurements were averaged for particles in the same size range and of the same particle habit. A technique was developed to calculate the asymmetry parameter from the observed angular data.

Values of asymmetry parameter for different particle types and size ranges were calculated and compared to available published data and parameterizations. The values for asymmetry parameter calculated from the PI-Nephalometer data ranged from .80 to .85 and were generally similar to or slightly higher than ray-tracing and experimental data for similar particles.