Dalton Minimum

The Dalton minimum in the 400 year history of sunspot numbers

The Dalton Minimum was a period of low sunspot count, representing low solar activity, named after the English meteorologist John Dalton, lasting from about 1790 to 1830 or 1796 to 1820, corresponding to the period solar cycle 4 to solar cycle 7.

Dalton Minimum and Temperature

Like the Maunder Minimum and Spörer Minimum, the Dalton Minimum coincided with a period of lower-than-average global temperatures. During that period, there was a variation of temperature of about 1 °C.

The cause of the lower-than-average temperatures during this period, or whether it is related to the low sunspot count, is not well understood. Recent papers have suggested that a rise in volcanism was largely responsible for the cooling trend.

While The Year Without a Summer, in 1816, occurred during the Dalton Minimum, the prime reason for that year's cool temperatures was the highly explosive eruption of Mount Tambora in Indonesia, which was one of the two largest eruptions in the past 2000 years.

See also

• Solar Variation
• Maunder minimum

References

• Komitov, Boris and Vladimir Kaftan (2004) "The Sunspot Activity in the Last Two Millenia on the Basis of Indirect and Instrumental Indexes: Time Series Models and Their Extrapolations for the 21st Century", in Proceedings of the International Astronomical Union, 2004, pp. 113-114.
• Wagner, Sebastian and Eduardo Zorita (2005) "The influence of volcanic, solar and CO2 forcing on the temperatures in the Dalton Minimum (1790–1830): a model study", Climate Dynamics v. 25, pp. 205–218, doi 10.1007/s00382-005-0029-0.
• Wilson, Robert M. (nd) "Volcanism, Cold Temperature, and Paucity of Sunspot Observing Days (1818-1858): A Connection?", The Smithsonian/NASA Astrophysics Data System, accessed February 2009.

Further reading

A detailed analysis with the auroral and solar data has been given by Wilfried Schröder, N.N. Shefov in a paper in Ann. Geophys. 2004. Also details can be found in Wilfried Schröder, Das Phänomen des Polarlichts (The Aurora in Time), Darmstadt, Wissenschaftliche Buchgeselllschaft 1984, and Science Edition, Bremen, 2000.