9. The dusty case We assume that dust is injected into the atmosphere when the surface stress exceeds some critical value. The value of dust flux is constant (3.7 E-6 kg/m^2/sec, White et al., 1997). The value of critical surface stress is reduced to 0.01 Pa. Instead of introducing background large scale wind, we reduce the value of critical surface stress. Initial distribution of wind, pressure and temperature are those of dust-free condition at LT = 6:00 of 6th day. The numerical integration is performed for 6 days. The visible optical depth is about 0.7 at 6th day (Fig.6). Fig.6: Time development of visible optical depth of dust.