Summary

The Spontaneous Ice Nucleation II (SPIN) project flew the Sabreliner in a continuation of earlier efforts to study high altitude atmospheric aerosols via sample collections and in-flight experiments, predominantly in wave clouds, where the time history of droplet and ice particle growth can be reconstructed (the "Spontaneous Ice Nucleation problem"). Liquid water microphysics were measured and compared with that predicted on the basis of a droplet growth model. Ice crystal samples were collected, studied, and compared with crystals formed in the laboratory. Air filter samples were taken to identify chemical constituents in the air and particle samples. A laboratory investigation of spontaneous ice nucleation was undertaken to further the understanding of cirrus cloud behavior. This project was run by Donald E. Hagen, Research Associate Professor at the University of Missouri-Rolla, and Andrew J. Heymsfield, Scientist at NCAR/MMM Division.