30+ Mount Tambora Cold Summer Background. Gloomy, cold rains fell throughout europe. Without volcanic forcing, it is less likely to have been as wet and highly unlikely to have been as cold. reference:
The 1815 eruption of mount tambora released massive amounts of sulfur dioxide, which formed sulfuric acid in the upper atmosphere.
But when mount tambora erupted, it expelled 36 cubic miles of debris into the atmosphere. The 1810's became the coldest decade on record. Mount tambora is centered in the image on the right on the sumbawa island, (southern) indonesia. It brought about the year without a summer.