Saturday, December 15, 2007

The Sun: Masker of the Earth's Deskiny?

It's not easy bein' me
Masker of me own deskiny
And I hates responsibiliky
It's not easy bein' me Popeye
The Sun gives us life-sustaining warmth and light. Yet the sun also bombards our space with deadly x-rays, gamma rays, high energy electrons, and atomic nuclei--which if not for Earth's atmosphere and magnetic field would kill us all. But wait--the sun's solar wind and magnetic field also shields the earth from dangerous radiation coming from outside the solar system. The Sun is clearly up to both good and bad. What else is the sun doing, that we should know about?

Recently, astrophysicists have become aware of the sun's interaction with the "global atmospheric electric current," and have started looking at the weather and climate implications.
Tinsley 2007 ... [demonstrates] the change in the ionospheric coupling from the solar wind that induces changes of the global electrical circuit ...

Reports of a variety of short-term meteorological responses to changes in the global electric circuit associated with a set of disparate inputs are analyzed. The meteorological responses consist of changes in cloud cover, atmospheric temperature, pressure, or dynamics. All of these are found to be responding to changes in a key linking agent, that of the downward current density, Jz, that flows from the ionosphere through the troposphere to the surface (ocean and land). As it flows through layer clouds, Jz generates space charge in conductivity gradients at the upper and lower boundaries, and this electrical charge is capable of affecting the microphysical interactions between droplets and both ice-forming nuclei and condensation nuclei.

...Thus, we propose that mechanisms responding to Jz are a candidate for explanations of sun–weather–climate correlations on multidecadal to millenial timescales, as well as on the day-to-day timescales analyzed here.
Outside the Cube

Scientists from the US, Europe, and other parts of the world are beginning to pay much more attention to the Earth-Sun interaction--and what it may involve.
Convection cells, made of plasma, an ionised and highly variable gas, are found at altitudes of hundreds kilometres over the polar caps. Their behaviour pattern is intimately linked to the response of the Earth’s magnetic environment to solar activity.

Although Earth is largely protected from the hazards of interplanetary space by the magnetosphere and atmosphere, they don't form an isolated bubble.

...One way to monitor this interaction is to study the convection cells. In the region, called the high-latitude ionosphere where they are located, the behaviour of the plasma cells strongly depends on the response of the magnetosphere to the orientation of the interplanetary magnetic field (IMF, an extension of the solar magnetic field, carried by the solar wind). This means that the behaviour of polar cap convection cells is a good tracer of the Sun-Earth connection.

Keep in mind that several mechanisms for sun-earth climate interaction are being proposed. These are somewhat different from Svensmark's solar wind/cosmic ray hypothesis on cloud formation. The astrophysicist community within NASA is said to be seriously divided over the question of the extent of solar variability influencing Earth's climatic trends. This could get interesting.

The following links provide some elementary scientific background about the interaction of solar radiation with Earth's global atmospheric electrical current.