Supercooled water droplet impacting-freezing behaviors on cold superhydrophobic spheres

•Supercooled water droplet impacting-freezing on superhydrophobic spheres is simulated.•The effects of sphere-to-droplet diameter ratio are emphatically investigated.•The Weber number affects the spreading more obviously at a smaller diameter ratio.•A smaller diameter ratio yields a larger maximum spreading area factor.•Morphology maps of rebound and adhesion for different diameter ratios are obtained.