In the period from mid-November 1985 through April 1986 the stratospheric aerosol profiles determined by lidar observations at the Mauna Loa, Hawaii Observatory indicated a persistent sequence of profiles characteristic of stratospheric volcanic aerosols. Aerosol layers were observed in two general altitude ranges. A high layer between about 25 and 27 km was detected in late November 1985 and again in late February and late March 1986. A lower layer, generally located between 20 and 23 km was present from early December 1985 through April 1986. These layers appear to have been due to the November 13, 1985 eruption of Nevado del Ruiz in Columbia. On the basis of these lidar data the impact of this volcanic plume on direct solar irradiance at 694 nm in Hawaii was estimated to have been an average diminution of about 0.4 per cent during the period December 1985 through April 1986. ¿American Geophysical Union 1987