A test of cirrus ice crystal scattering phase functions

Abstract

In-situ ice crystal scattering has been measured in cirrus cloud with the Small Ice Detector laser scattering probe. Using light scattered from single particles (maximum dimension ∼<100 μm) at 4–10° and 20–40° we have tested ice crystal scattering phase functions for spheres, hexagonal columns, hexagonal plates, polycrystals an aggregate of columns and an analytic function. We find that phase functions that lack a pronounced 22° halo are the best representatives for the example data presented here. Spherical ice particle phase functions do not satisfy the measurements.