Tambora Volcano near bottom of map                                Tambora Volcano from above

http://volcano.und.nodak.edu/vwdocs/volc_images/southeast_asia/indonesia/krakatau.html
http://vulcan.wr.usgs.gov/Volcanoes/Indonesia/Tambora/description_tambora.html
http://vulcan.wr.usgs.gov/Glossary/VolcWeather/description_volcanoes_and_weather.html
http://vulcan.wr.usgs.gov/LivingWith/VolcanicFacts/deadly_eruptions.html
http://vulcan.wr.usgs.gov/Volcanoes/Indonesia/Maps/map_indonesia_volcanoes.html
http://volcano.und.nodak.edu/vwdocs/vw_hyperexchange/largest_erups.html
http://volcano.und.nodak.edu/vwdocs/volc_images/southeast_asia/southeast_asia.html
http://www.infoplease.com/ipa/A0197833.html
http://www.cotf.edu/ete/modules/volcanoes/vclimate.html
http://volcano.cs.und.nodak.edu/vwdocs/Gases/toba.html
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Henry Stommel, the famous atmospheric/ocean scientist, wrote with his wife a book on Tambora and his wife a book on Tambora and its climate effects. It is Volcano Weather: The Story of 1816, the Year Without a Summer, Seven Seas Press, Newport, RI, USA, 1983. They went to great  efforts to assemble data, not only for 1816 but also for a considerable
period before and after, mostly for the New England region.
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Tambora, Mount

Indonesian Gunung Tambora dormant volcanic mountain on the northern coast of Sumbawa island, Indonesia. Now 9,354 feet (2,851 m) high, it erupted violently in 1815, when it lost much of its top and caused the death of 50,000 islanders and destroyed the homes of 35,000 more. Before that eruption Mount Tambora was 13,000 feet (4,000 m) high.

Location: 8.3S, 118.0E
Elevation: 9,348 feet (2,850 m)
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Tambora is a stratovolcano, forming the Sanggar peninsula of Sumbawa Island. The diameter of the volcano at sea-level is about 38 miles (60 km). Prior to the 1815 eruption, the volcano may have been as tall as 13,000 feet (4,000 m). The 1815 eruption formed a caldera about 4 miles (6 km) in diameter. The caldera is 3,640 feet (1,110 m) deep.

The 1815 eruption of Tambora caused the "Year without a Summer." Daily minimum temperatures were abnormally low in the northern hemisphere from late spring to early autumn. Famine was widespread because of crop failures.

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Sources:

Francis, P., 1994, Volcanoes a planetary perspective: Oxford University Press, New York, 443 p.

Self, S., Rampino, M.R., Newton, M.S., and Wolff, J.A., 1989, Volcanological Study of the Great Tambora Eruption of 1815: Geology, v. 12, p. 659-663.

Sigurdsson, H., and Carey, S., 1989, Plinian and Co-Igmibrite Tephra Fall from the 1815 Eruption of Tambora Volcano: Bulletin of Volcanology, v. 51, p. 243-270.

Stothers, R.B., 1984, The Great Tambora Eruption of 1815 and Its Aftermath: Science, v. 224, 1191-1198.

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Largest Explosive Eruptions Since 1400 AD
Greater Than or Equal to 5

Modified from Table 3 in Newhall, CG, and S Self, 1982, The volcanic explosivity index (VEI): An estimate of explosive magnitude for historical volcanism: Journal of Geophysical Research87, 1231-1238.  Additional eruptions added from tree ring data reported in Table 2 of Briffa, KR, PD Jones, FH Schweingruber & TJ Osborn, 1998, Influence of volcanic eruptions on Northern hemisphere summer temperature over the past 600 years: Nature 393, 450-455.  Note that other large eruptions occurred during the last 600 years, according to tree ring and ice core data, but are not indicated here because the source volcano is unknown (e.g. 1809).

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Volcanoes & Climate
Volcanic eruptions can alter the climate of the earth for both short and long periods of time. For example, average global temperatures dropped about a degree Fahrenheit for about two years after the eruption of Mount Pinatubo in 1991, and very cold temperatures caused crop failures and famine in North America and Europe for two years following the eruption of Tambora in 1815. Volcanologists believe that the balance of the earth's mild climate over periods of millions of years is maintained by ongoing volcanism. Volcanoes affect the climate through the gases and dust particles thrown into the atmosphere during eruptions. The effect of the volcanic gases and dust may warm or cool the earth's surface, depending on how sunlight interacts with the volcanic material.

Volcanic dust blasted into the atmosphere causes temporary cooling. The amount of cooling depends on the amount of dust put into the air, and the duration of the cooling depends on the size of the dust particles. Particles the size of sand grains fall out of the air in a matter of a few minutes and stay close to the volcano. These particles have little effect on the climate. Tiny dust-size ash particles thrown into the lower atmosphere will float around for hours or days, causing darkness and cooling directly beneath the ash cloud, but these particles are quickly washed out of the air by the abundant water and rain present in the lower atmosphere. However, dust tossed into the dry upper atmosphere, the stratosphere, can remain for weeks to months before they finally settle. These particles block sunlight and cause some cooling over large areas of the earth.

Volcanoes that release large amounts of sulfur compounds like sulfur oxide or sulfur dioxide affect the climate more strongly than those that eject just dust. The sulfur compounds are gases that rise easily into the stratosphere. Once there, they combine with the (limited) water available to form a haze of tiny droplets of sulfuric acid. These tiny droplets are very light in color and reflect a great deal of sunlight for their size. Although the droplets eventually grow large enough to fall to the earth, the stratosphere is so dry that it takes time, months or even years to happen. Consequently, reflective hazes of sulfur droplets can cause significant cooling of the earth for as long as two years after a major sulfur-bearing eruption. Sulfur hazes are believed to have been the primary cause of the global cooling that occurred after the Pinatubo and Tambora eruptions. For many months, a satellite tracked the sulfur cloud produced by Pinatubo. The image shows the cloud about three months after the eruption. It is already a continuous band of haze encircling the entire globe. You can learn more about the cooling effects of sulfur hazes by clicking

Volcanoes also release large amounts of water and carbon dioxide. When these two compounds are in the form of gases in the atmosphere, they absorb heat radiation (infrared) emitted by the ground and hold it in the atmosphere. This causes the air below to get warmer. Therefore, you might think that a major eruption would cause a temporary warming of the atmosphere rather than a cooling. However, there are very large amounts of water and carbon dioxide in the atmosphere already, and even a large eruption doesn't change the global amounts very much. In addition, the water generally condenses out of the atmosphere as rain in a few hours to a few days, and the carbon dioxide quickly dissolves in the ocean or is absorbed by plants. Consequently, the sulfur compounds have a greater short-term effect, and cooling dominates. However, over long periods of time (thousands or millions of years), multiple eruptions of giant volcanoes, such as the flood basalt volcanoes, can raise the carbon dioxide levels enough to cause significant global warming.
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