Special thanks to Rob Bauer of the National Snow and Ice Data Center for his time, effort and advice in obtaining data for this research. The SSM/I data were supplied in a straightforward and timely fashion by the Marshall Space Flight Center (MSFC) Distributed Active Archive Center (DAAC). The C-band radar data were supplied by Lee Kelley of the National Weather Service, Anchorage, AK. The Mie program for calculating the efficiency factors for a single spherical particle was supplied by W. J. Lentz. This research was aided by interaction with Jim Weinman and Alex Kostinski. Special thanks to Ralph Ferraro of the Microwave Sensing Group, NOAA/Satellite Research Lab for suppling reference materials and comments. Thanks to all the people that reviewed and commented on the paper. Funding was provided by NASA through the Volcano/Climate program and the COMET program of NOAA.