Here's a website that I found that explains things a little more scientifically:
http://sheldonbrown.com/brandt/wind.html
Here are some of the "key" statements:
"Wind drag is a nonlinear function of the relative wind. That is, drag does not increase in proportion (linearly) to wind but rather with the square of its speed relative to the rider."
"Although inline winds add or subtract directly to drag, they do not similarly affect the power required to overcome that drag. For instance, standing still in a 15mph wind requires no power because power is the product of inline drag and rider speed."
"Drag is proportional to the square of relative wind-speed while power is the product of the inline portion of that drag and rider speed. Thus, required power (in still air) increases as the cube of rider speed."
As you can see...as soon as you start seeing "square or cube of a rider's speed"...or "drag is proportional to the square...", that wind resistance, drag, or speed are not linear relationships.
Now after reading all of that...you are allowed to let your head explode!!!
- Nick