On August 20 1991, unusual, hazy clouds were encountered by commercial jet aircraft flying over continental SE Australia. Image data from the AVHRR on board the NOAA satellites have been used to discriminate the clouds from water/ice clouds. The clouds were again observed over Australia by lidar eight days later, presumably after a complete circumnavigation in the zonal winds of the southern mid-latitudes. The lidar measurements revealed a strong scattered signal from a layer situated near 12 km above the surface. The satellite and lidar data indicate that the clouds were of volcanic origin and we suggests that they originated from the Mt Hudson eruptions in Chile. We have used a numerical model to simulate the transport of the volcanic clouds and find good agreement between the projected position of the clouds and observations. ¿ American Geophysical Union 1992