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Large Scale Climate Change. Glaciations in time. 1. Variations of solar output. Long term increase in luminosity Moderate to short term changes in fusion rate and diameter Moderate to short term surface variations. Sun’s Internal Structure. Internal Structure of Sun.
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1. Variations of solar output. Long term increase in luminosity • Moderate to short term changes in fusion rate and diameter • Moderate to short term surface variations
Controls of Stellar Fusion • Fuel • Pressure • Temperature • Sun shrinking about 0.1% /100 years becoming more energic
Above: Yearly-averaged sunspot numbers from 1610 to 2008. Researchers believe upcoming Solar Cycle 24 will be similar to the cycle that peaked in 1928, marked by a red arrow. Credit: NASA/MSFC
Sun Spot Cycles • Observations 527 BC • 8 – 16 years • Alternating solar polarity • 10 year cycles AD 800-900 • 10.2 year cycles 1914 – • 12 – 14 year cycles 1656-1723, 1799-1833,1870-1913
Solar Activity Index • Weighted frequency of sun spots and auroral displays • 14C formation inverse to SAI • Dates SAI # of Glaciers advancing • AD 1011-1211 1 05 3 • AD 1212-1387 95 2 • AD 1388-1586 91 6 • AD 1587-1798 81 36 • AD 1799- 1879 91 20 • AD 1880-1964 109 5 • Maunder Minimum 1645-1717 Little Ice Age
Sunspot cycle from 1700 with Dalton Minimum and expected levels.Source: Badalyan, Obridko and Sykora
The Dalton Minimum was a period of low solar activity, named for the English meteorologist John Dalton, lasting from about 1790 to 1830.[1] Like the Maunder Minimum and Spörer Minimum, the Dalton Minimum coincided with a period of lower-than-average global temperatures. The Oberlach Station in Germany, for example, experienced a 2.0° C decline over 20 years.[2] The Year Without a Summer, in 1816, also occurred during the Dalton Minimum.
2. Cosmic dust vails • Rotation (about 250,000,000 years) • Translation (130-600 Km/Sec)
Interstellar Stuff • Calculations suggest that there is lots of stuff not in observed bodies • Stars form where stuff is compressed at the leading edge of a galaxy • Not all stuff into stars • Stuff not uniformly distributed • Stuff likely to slightly obscure the sun and reduce insolation
3. Variations in Earth - Sun Relations (Astronomical Theory, Milankovitch Cycles) • One of the most popular theories • Used to explain several types of phenomena through geologic time • Can be modeled simply
Milankovitch CycleCroll- Milankovitch Cycle • Proposed by geologist James Croll (1821-1890) • “Climate and Time in their Geological Relations” 1867 • Serbian astronomer Milutin Milankovitch (1879-1958) • calculated the slow changes in the earth's orbit by careful measurements of the position of the stars • Mathematical Climatology and the Astronomical Theory of Climatic Changes1930 • Major publications 1920, 1941
Components • Earth’s Orbit • Earths Tilt • Earths Precession
Orbit Data • 2004 • Perihelion Jan 4 18 Aphelion July 5 11 • Equinoxes Mar 20 06 49 Sept 22 16 30 Solstices June 21 00 57 Dec 21 12 42 • 2005 • Perihelion Jan 2 01 Aphelion July 5 05 Equinoxes Mar 20 12 33 Sept 22 22 23 Solstices June 21 06 46 Dec 21 18 35
Orbital Data • Dates and times of aphelion and perihelion of Earth:2010-Jan-03 00-hour Earth at perihelion 0.983290 AU (91,422,023 miles or 147,098,036 km)2010-Jul-06 11-hour Earth at aphelion 1.016702 AU (94,528,559 miles or 152,096,452 km)
Eccentricity • About 100,000 years • Change in orbit shape and center • Main component 110,000 years, minor component 413,000 years • Currently more circular • Jan 3 perihelion, July 4 aphelion • 6% difference between January and July • At Maximum ellipse • 20 – 30% difference
Tilt (inclination to plane of ecliptic) • Range 21.8o to 24.4o • Period 41,000 years • Currently about midpoint
Precession (wobble) • North pole pointing at the North Star, to having the North pole pointing at the star Vega • 22,000 year cycle is composed of a 19,000 cycle and a 23,000 year cycle).
4. Atmospheric Conditions • Composition • N2, O2, Greenhouse Gasses (H2O, • Particluates
Dust Veil Index • DVI = 0.97 Rmax Emax Tmo • DVI = 52.5 Tdmax Emax Tmo • DVI = 4.4 Q Emax Tmo