The Atmospheric Radiation Measurement (ARM) Program was created in 1989 by the U.S. Department of Energy (DOE) to develop several highly instrumented ground stations to study cloud formation processes and their influence on radiative transfer. As the program evolved to include additional measurements of aerosol and precipitation, the original ground sites were supplemented with three mobile facilities and an aerial facility. This comprehensive scientific infrastructure and data archive were designated by DOE as a scientific user facility—the ARM Climate Research Facility—in 2003, and are freely available for use by scientists worldwide.