Resumen
Solar radiation data (global and diffuse) provided by the Solar Radiation Observatory of the Institute of Geophysics of the National University of Mexico, corresponding to the period 1980 to 1985, are analyzed. Two sets of data where selected. The first contains all 10 and 11 hours (L.T.) data and the second contains only the values corresponding to maximum insolation (MI), as recorded by a Stokes heliograph. Therefore the influence of clouds is minimized with the second, corresponding to cloud free condition. From the analysis of the annual and monthly averages the effects of El Chichon (1982) are clearly visible in diffuse radiation. The effects of El Nino phenomenon (increases of the surface temperature of the Pacific Ocean) from 1982 to 1983, are apparent in the global radiation averages.