Conflicts of interest/Competing interests: Not applicable Availability of data and material: all the data used in this work are publicly available. ISD cloud data are accessible from www.ncdc.noaa.gov/isd/data-access, and EECRA cloud data from NCAR at climateguide.ucar.edu/climate-data. The CALIOP satellite data come from the GCM-Oriented CALIPSO Cloud Product (GOCCP) at climserv.ipsl.polytechnique.fr/cfmip-obs/Calipso_goccp.html. ERA5 reanalyses are available from https://cds.climate.copernicus.eu and MERRA-2 from gmao.gsfc.nasa.gov/reanalysis/MERRA-2/data_access. CMIP6 data can be downloaded from esgfnode.llnl.gov/search/cmip6.