A user friendly web-version of the ERA-40 climatological Atlas has been made available. It includes all the material in the printed version of the Atlas; ERA-40 Report Series No. 19. The Atlas describes the climate during 1979 - 2001, the period with the best and most time-consistent product quality for the globe as a whole. The Atlas contains surface and column-integrated fields, and upper-air fields derived on pressure levels, on isentropic levels and on the 2 pvu potential-vorticity level from values on the models native hybrid levels. Also included are the invariant fields used in the data-assimilation system. The climate of the period 1979 - 2001 is presented for the four seasons, the annual average and the interannual variability. These products are based on the ERA-40 monthly/ diurnal averages together with six-hourly analysis and forecast fields. A selection of time series, showing for example the quasi-biennial oscillation of stratospheric winds, is presented for the full period 1958 - 2001. ERA40 Atlas available at https://sites.ecmwf.int/era/40-atlas/docs/index.html