Presents information on the seasonal, latidudinal, longitudinal and day-to-day variability of atmospheric properties at levels between the surface and 80 km. The systematic variation of atmospheric properties is shown for altitudes up to 80 km by a family of models, comprising the reference atmospheres tropical, sub-tropical, mid-latidude, sub-arctic and arctic. Furthermore temporal and spatial variations and frequency distributions of observed temperatures and densities are given.