The physical and chemical influences on ice nucleation processes are poorly understood at present, and understanding the transformations from aerosol particles to ice is of high interest in the field of atmospheric sciences. This collaborative project builds upon previous work by the lead investigator - in this case combining aerosol and ice nucleus measurements at a field site to determine the chemical composition of aerosols that nucleate ice as well as characterizing those transformations from aerosol particles to ice crystals. Through collaborations between Colorado State University (CSU), University of Colorado (CU) and a government laboratory the investigators will use a combination of methods, including the CSU continuous flow diffusion chamber for ice nuclei number density measurements, electron microscopy for size and composition of nucleated ice particles, and the NOAA Aeronomy Laboratory Particle Analysis by Laser Mass Spectrometry instrument and CU aerosol mass spectrometer to continuously analyze size-resolved chemical residuals of freshly nucleated ice particles in real time. The investigators will compare physical and chemical characteristics of particles active as ice nuclei with ambient atmospheric aerosol to determine which characteristic factors are associated with the ability to form ice crystals at typical cirrus temperatures and supersaturations. The results of this research should be important for understanding the role of aerosols in global climate as well as their impacts on the chemistry of other species. The results of the research should have an impact on climate and global change relative to issues related to anthropogenic influences on clouds and radiative forcing - particularly with respect to cirrus formation. Experimental data will provide new data to constrain climate models, and make parameterizations more robust and representative. The project involves interdisciplinary collaboration between two university groups and a government laboratory. Contributions to education include support for postdoctoral researchers and graduate students to gain professional research experience.