Volcanic winter
A volcanic winter is a reduction in global temperatures caused by droplets of sulfuric acid obscuring the Sun and raising Earth's albedo (increasing the reflection of solar radiation) after a large, sulfur-rich, particularly explosive volcanic eruption. Climate effects are primarily dependent upon the amount of injection of SO2 and H2S into the stratosphere where they react with OH and H2O to form H2SO4 on a timescale of a week, and the resulting H2SO4 aerosols produce the dominant radiative effect.