[justa-hairyape]

And concerning the sun being a constant, it is not. Solar Activity varies quite dramatically across numerous vectors. Total Irradiance is not that important since the metric is screwed up by the nature of the sunspots themselves. The spots have a dark region that emits less light and a bright region that emits more light. So their affects on total emitted light are partially canceled. One of the real vectors one must look to see large scale variations is electromagnetic radiation outside the normal visible light spectrum (UV for example). It varies quite a bit. Also, solar wind, magnetic flux and cosmic ray interference are important vectors. And I am sure there are a few more that us apes is clueless about.

[justa-hairyape]

CME’s are also important. Coronal Mass Ejections. That mass is traveling at very fast velocities.

[dr_who]

So their affects on total emitted light are partially canceled.

In terms of electromagnetic radiation at least, I wouldn't expect them to have any measureable effect on the ~1300 W/m^2 we get from the sun, given how much surface area that the sun has. And what's so special about UV? As for subatomic particles that probably mostly bombard the poles, it would be interesting to know how that affects polar weather patterns or whether radiation in the upper reaches of the atmosphere have much of relevance to the lower atmosphere which I guess is what we're really concerned about.