Thermal emission at 6.8 &mgr;m and particle-scattered radiation at 1.9 &mgr;m from the El Chichon aerosol cloud were measured by instruments on board the Solar Mesosphere Explorer satellite. The cloud moved westward circling the globe in twenty-one days. During its initial formation the cloud was centered at an altitude of 27 km and was confined to the latitude band between the equator and 30¿N. At the 27 km level, the maximum density was reached eight to nine weeks after the eruption. Following that time, the maximum in the density gradually moved lower in altitude.