Relative velocities between dust aggregates in a protoplanetary disk computed according to a) Weidenschilling (1977b); b)Andrews & Williams (2007); and c)Desch (2007) at 1 AU and a turbulence parametre of α = 10^-5. The velocity profiles are labelled in units of m s^-1. The hashed boxes represent the collisions observed during the SPACE experiment (see text for more details). The dashed contour displays the minimum sticking velocity measured during the SPACE experiment for both size distributions. The dotted contour displays the same minimum sticking velocity in the case of aggregate-aggregate collisions instead of aggregate-cluster collisions (see text for details).