This report provides descriptions of environmental models used in the near-earth environment for the analysis of earth-based and satellite data. Included are models of the ionosphere, atmosphere, radiation belt, Earth's magnetic field, and orbital prediction. These models are used at PL for a variety of purposes, in particular, for the analysis of experimental data obtained from ground based instruments and, where applicable, instruments carried on balloons, rockets, and satellites. Some of the models described here were developed at PL based upon such measurements. For many of the models described here, computer output is provided together with estimates of computer (CPU) times required to generate such output. The computer codes (subroutines) for these models are frequently incorporated into programs used for data analysis and reduction, as well as mission planning. It is hoped that this report will serve as a useful reference for planning such future missions.