Schematic illustration of the dust torus model by Kawaguchi & Mori. Blue denotes hot T ~ 1600 K dust visible at 1−2 μm, red denotes cooler T ~ 800 K dust visible at ~4 μm. The single black numbers left and right of the rim give the lags along the torus rim at 1−2 μm and at ~4 μm, respectively. Note the foreshortening of the lags in the high-altitude part of the torus rim. The mean lags of the equatorial zones (A and C) and the entire 2π integrated torus rim (B and D) are given, adopting a constant dust density distribution along the rim.