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Thread: The Medieval Maximum

  1. #1
    Join Date
    Dec 2005

    The Medieval Maximum

    Sunspots are areas of intense magnetic fields, which inhibits heating by convection and the area cools from the average of 5,800 deg K to around 4,000 to 4,500 deg K.

    However, sunspots are still brighter than electric arcs. They just look darker next to the hotter, normal material of the sun when viewed through a heavy filter.

    I think the following quote from Wiki:Sunspot is rather interesting:

    The number of sunspots has been found to correlate with the intensity of solar radiation over the period - since 1979 - when satellite measurements of radiation are available. Since sunspots are dark it might be expected that more sunspots lead to less solar radiation. However, the surrounding areas are brighter and the overall effect is that more sunspots means a brighter sun. The variation is very small (of the order of 0.1%).

    During the Maunder Minimum in the 17th Century there were hardly any sunspots at all. This coincides with a period of cooling known as the Little Ice Age.

    The Maunder Minimum coincided with the middle and coldest part of the so-called Little Ice Age, during which Europe and North America, and perhaps much of the rest of the world, were subjected to bitterly cold winters. Whether there is a causal connection between low sunspot activity and cold winters is the subject of ongoing debate (e.g. see Global Warming).
    I find it interesting that suspot activity over the last 70 years has been higher than any time in the last 700 years, and that during the 400-year Medieval Maximum, or Medieval Warm Period, as it's now called, sunspots were as plentiful as they are today, and temps were unusually warm throughout that period.

    There's a video on YouTube which makes this correlation as well, but any time a link find it's way here to this board, it's dismissed as "bunk," despite the fact that climatologists themselves know these periods and their correlation with suspots rather well.

  2. #2
    Join Date
    Dec 2005
    To quell (hopefully) some of the head-slapping which has probably already occurred, here's a link:

    U.S. National Report to IUGG, 1991-1994
    Rev. Geophys. Vol. 33 Suppl., © 1995 American Geophysical Union

    By the way, that report was typed up by:

    Paul A. Mayewski, Glacier Research Group, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham


    Michael Bender, Graduate School of Oceanography, University of Rhode Island, Kingston

    Here's a link to their References.

    I think it's also quite interesting to note that "...the period of the sunspot cycle was identical to the period of changes of geomagnetic activity at Earth...", and it's our geomagnetic field which plays a major role in determining how much solar radiation arrives here on Earth.

    Even the U.S. Geological Survy notes the correlation, and provides a fairly detailed 6-page summary which neatly explains the various processes involved, correctly noting that while changes in our sunspots and our magnetic field have a small effect on the overall solar irradiance, they have a much larger influence on ultraviolet, extreme ultraviolet, and X-rays:

    Far more variable than changes in total solar irradiance are changes in
    amount of energy emitted as ultraviolet, extreme ultraviolet, and X-rays, and
    in the continuous outflow of ionized solar particles (solar wind), which
    controls the properties of the Earth’s magnetosphere.

  3. #3
    Join Date
    Sep 2004
    Shouldnt this be in general science ?

    This is also one of the reasons that global warming is not as well known as some would have you believe

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