group committees." A maximum of 0.1% of the membership can be elected each year. Medals The Charles A. Whitten Medal (established 1984), named after Charles A. Whitten, a former AGU General Secretary and geodesist, "for outstanding achievement in research on the form and dynamics of the Earth and planets." The Devendra Lal Memorial Medal (established 2016) was named after Devendra Lal. Lal had a founding role in developing the field in which cosmic rays produced isotopes on Earth and are used as tracers to investigate a wide range of Earth Science problems. The Medal is awarded "for outstanding Earth and/or space sciences research by a scientist belonging to and working in a developing country." The James B. Macelwane Medal (established 1961), named after James B. Macelwane, a former AGU president who was deeply interested in teaching young scientists, "to be awarded annually for significant contributions by outstanding young scientists." Recipients must be no more than 10 years past their highest degree. The Joanne Simpson Medal (established in 2017), named after Joanne Simpson, the first woman in the United States to receive a PhD in meteorology, "for significant contributions to the earth and space sciences by an outstanding mid-career scientist." The John Adam Fleming Medal (established 1960), named after John Adam Fleming, a major contributor to magnetic standards and measurements, "for original research and technical leadership in geomagnetism, atmospheric electricity, aeronomy, space physics, and related sciences." The Maurice Ewing Medal (established 1974 and co-sponsored by the United States Navy), named after Maurice Ewing, a major contributor to oceanography, "for significant original contributions to the scientific understanding of the processes in the ocean; for the advancement of oceanographic engineering, technology, and instrumentation; and for outstanding service to the marine sciences." The Harry H. Hess Medal (established 1984), named after Harry Hammond Hess, who made major contributions to the study of the oceanic lithosphere, "for outstanding achievements in research of the constitution and evolution of Earth and other planets." The Inge Lehmann Medal (established 1995), named after Inge Lehmann, the discoverer of the Earth's inner core, "for outstanding contributions to the understanding of the structure, composition, and dynamics of the Earth's mantle and core." The Robert E. Horton Medal (established 1974), named after Robert E. Horton, who provided many of the analytical concepts for understanding the hydrologic cycle "for outstanding contributions to hydrology." The Roger Revelle Medal (established 1991), named after Roger Revelle,