Left: size distribution at different distances in a disk composed of 70% ice and 30% silicate, simulated with ACE. Curves depict the normal geometrical optical depth per size decade, as a function of size. The straight lines show power laws with q = 3.0 and 3.7 for comparison. (Their height is arbitrary.) Right: radial profiles of the optical depth. Symbols: partial contributions to the optical depth by several selected sizes. Each contribution is normalized to the unit size decade around that size. Solid line: the total optical depth of the disk.