Professor Ellingson's career has been devoted to teaching and research in the area of physical meteorology - thermodynamics, cloud physics and radiative transfer. His primary research activities are concerned with the measurement, calculation and analysis of atmospheric radiation quantities. These activities have as goals the development of techniques for including radiative transfer in climate models and for remotely sensing radiation budget parameters from space. He is the Secretary of the International Radiation Commission (IRC) of the International Association of Meteorology and Atmospheric Physics (IUGG); Chairman of the International Intercomparison of Radiation Codes for Climate Models (ICRCCM) a working group of the World Climate Research Program; a member of the Editorial Board of the Journal of Quantitative Spectroscopy and Radiative Transfer; Chair the U.S. Department of Energy (DOE) Atmospheric Radiation Meaasurement (ARM) program Science Team Executive Committee, and Mission Scientist for DOE Unmanned Aerospace vehicle program. Professor Ellingson is also the Chair of the Department of Meteorology at the Florida State University.