The eruption of Mount Tambora in 1815 threw enough ash into the atmosphere to cool the northern hemisphere through the following year. Crops failed across New England and western Europe, and June brought snow to parts of the United States. Kept indoors by the wet Swiss weather that summer, a house party near Geneva agreed to write ghost stories; one of them became Frankenstein.
Why this oneA volcano in Indonesia is part of the reason Frankenstein exists.