Ejection-velocity field of the hybrid model, as a function of day relative to perihelion (lower x-axis) and heliocentric distance (upper x-axis). The velocity is parametrised in the model by Eq. (3). The fastest particles correspond to a size of 10 μm. In addition, the velocities of the 100 μm, 0.1 cm, and 1 cm sized particles are shown. The slowest velocity in the model is red-labelled as V_min, which corresponds to the largest particles (from 1 cm to 40 cm; see Fig. 6, right panel).