The second primary factor involves converting that water gas (water vapor) into liquid water (cloud moisture). Now gamma rays help with the conversion of vapor to water. The more water vapor in the atmosphere, the more liquid water can be converted. Basically in a high gamma ray environment the atmosphere will have less water vapor and more water moisture.
In a nutshell - Your normal Texas rain was actually deposited in the Western Mountain ranges this year.
Sunspots are caused by magnetic field changes on the sun. Those field changes also tend to shield us from cosmic rays. (Cosmic rays are charged, remember, and charged particles will change their path in a magnetic field.) More sunspots, less cosmic rays. Less sunspots, more cosmic rays.
What the CERN guys have shown is that cosmic rays cause particles to form in the upper atmosphere that seed cloud formation. More clouds increase the earth's "albedo" (reflectivity), lowering surface temperature (b/c more solar radiation is reflected back into space).
Now the progression is:
more sunspots -> fewer cosmic rays -> fewer clouds -> warmer earth
less sunspots -> more cosmic rays -> more clouds -> cooler earth
It's been known for some time that more sunspots seemed to correlate to a warmer climate. This science explains why.