Evolution of the properties of a supergranular cell. An animation is available online. See Appendix A for details. Top left: horizontal velocity magnitude Vh_mag (gray levels) and families (TFG) at time 05:02. Top right: same plot at 05:36; families are represented by various individual colors. Middle left: longitudinal magnetic field (yellow and white) and families (TFG) at time 05:02. Middle right: same plot at 05:36. Bottom left: horizontal velocity magnitude Vh_mag (gray levels), families (TFG), absolute value of the longitudinal magnetic field (white isocontours) and velocity divergence (blue for negative, yellow for positive) at time 05:02; bottom right: same plot at 05:36.