Satellite image of atmospheric sulphur dioxide (SO2) after the eruption of El Chichon, Yucatan, Mexico. El Chichon erupted on 28 March 1982 & again on the 3rd & 4th of April. This image, the last in a series of 4, relates to data obtained on April 10th by the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus-7 satellite, an instrument normally dedicated to measuring atmospheric ozone. The colour scale at right shows concentration of SO2, with black representing the highest levels. In this image the SO2 plume is dispersing, having weakened & moved north & westwards from its original location over the Yucatan peninsula.