Stratospheric sulfate layer
From Glossary of Meteorology
stratospheric sulfate layer
( Also called Junge aerosol layer.) A region in the lower stratosphere (approximately 15–25 km in altitude and worldwide) where submicrometer-sized particles composed of aqueous sulfuric acid are present.
Oxidation of sulfur compounds (primarily carbonyl sulfide, OCS, and sulfur dioxide, SO2) is believed to be the source of sulfuric acid (H2SO4). Volcanic eruptions directly inject large quantities of H2S or SO2 into the stratosphere, causing large increases in the amount of particulate sulfuric acid. The particles undergo a slow falling-out process (timescale of years) into the lower atmosphere. Because these sulfuric acid particles are present in the ozone layer, heterogeneous chemical reactions that occur on them can have a significant effect on ozone by influencing the abundance of trace species that affect ozone concentrations.
Junge, C. E., C. W. Chagnon, and J. E. Manson 1961. Stratospheric aerosols. J. Meteor.. 18. p.81.