volcanic winter

noun1

1. •
   A reduction in global temperatures caused by volcanic ash and droplets of sulfuric acid obscuring the Sun and raising Earth's albedo (increasing the reflection of solar radiation) after a large, particularly explosive volcanic eruption.

   • People who lived through the Year Without a Summer, 1816, had no way to know at the time that they were living through a volcanic winter; some thought that the end times were beginning.