The talk will focus on retrieval and validation of cloud fraction climatologies derived from polar-orbiting (AVHRR) and geostationary sensors (MVIRI, SEVIRI) in a frame of ESA Cloud_cci and CMSAF projects. Validation of both datasets requires a high frequency of ground-based observations to allow for: timely collocations (for polar-orbiting satellites) and resolved diurnal cycle (for geostationary satellites). We will present a new dataset of 10-minute cloud amount estimates calculated from ground measurements of long-wave incoming radiation by means of the Bayesian Automatic Cloud Detection Algorithm (BACADA) at the Baseline Surface Radiation Network. Finally, we will look at climatological changes of cloud fraction in the last 3 decades, as well as at the consistency among trends and variability of cloud fraction, surface solar radiation and  top-of-atmosphere radiation over Europe.