[Phys-L] Re: solar cycle

[Gary Turner <turner@MORNINGSIDE.EDU>]

While there is almost certainly a link between global climate and solar
activity, and trends tend to indicate a tie to the 11-year cycle, it is a
stretch to say that droughts match the cycle (which implies that droughts
occur regularly on an 11-year cycle).  There are actually 2 issues here, the
weak link between occurence of global weather conditions (every 11 years),
and the much stronger link between global climate and averaged sunspot
number - which happens to indicate that the earth should have been warming
over the last, relatively active, 100 years.

Anyway, back to your question.  The total luminosity of the sun actually
rises at periods of large sunspot numbers, even though the sunspots
themselves are darker.  The rise is not very significant, but it does go up.
 What makes this really interesting though is that it is not a uniform
increase.  Irradiance from some wavelengths goes up substantially, while
others don't change much at all.  Whether or not there is a "resonance-like"
response of the Earth to one of these wavelengths is still active research I
believe.

Then there is the whole magnetic field issue.  A few years ago, I came
across some data that correlated (or anti-correlated, I can't remember)
global cloud cover with cosmic ray flux - maybe not a cause-effect
relationship, but possibly linked through solar activity because of the way
the magnetic field can affect cosmic ray flux.  The interactions between the
magnetic field and the upper atmosphere, and the effect that that has is
also current research (I believe).

And more interesting yet (for historians), the Vikings had a 7-year weather
pattern identified, before the occurence of the Maunder minimum which reset
the solar dynamo - leading to speculation that whatever tie there is to the
current weak 11-year weather cycle may be only a couple hundred years old.


On Tue, 15 Feb 2005 15:06:26 -0500, Anthony Lapinski
<anthony_lapinski@PDS.ORG> wrote:

> Sunspots follow a 22-year cycle (return to same polarity), and this cycle
> matches droughts on Earth. As the sunspot numbers increase, oceans become
> warmer. But isn't the Sun's surface cooler during these times? How can a
> cooler solar surface cause the Earth to warm up? I've never understood
> this. Does it have to do with the increased solar magnetic activity that
> heats the corona?