Stratospheric dust layers photographically observed in the altitude range 16-28 km from a balloon gondola floating at 36.6 km altitude on 3 May 1982 over southern France are identified as originating from the 4 April eruption of the Mexican El Chichon volcano. The identification is compatible with the zonal air motions leading to lidar detections over Japan, United States and Italy. The observations confirm the eastward motion of part of the injected material below 20 km altitude and the westward motion above this altitude. They imply a northward component of the meridional motion of the order of 20° (from 17°N to 37°N) in one turn around the Earth. The observation of scattered sunlight in blue and red light allows to deduce some optical properties of the aerosol, mainly those implied by the wavelength dependence of the scattering efficiency being highly variable, particularly above the Junge layer.