I'm not an intelligent man, nor do I play one on T.V.
That being said, here's my thinking on the subject. I've also often noticed that when achieving a speed equal to or in excess of 30 mph the wind seems to be much less buffeting than when riding into a strong headwind at a much slower speed.
I suspect it has something to do with the force driving the air. I compare moving through air to moving through water. I can see the water and it helps me to envision what might be happening as we attempt to move against that 25 mph head wind.
Imagine running or swimming against a strong current. There will be a constant force of water pushing against you impeeding your foreward motion. Now imagine swimming through calm water. You can easily slice through the motionless liquid gently pusing it aside and around your body. If you could achive the speed of the strong current previously mentioned, I believe you would still not feel the same resistance from the water as you did swimming slower against the current.
I suspect it's much the same with air, much easier to slice through still air than to overcome on-rushing air. I can't help but wonder if once you start slicing through the calm air, a current sets it's self up on each side of your body helping to draw the air past you as you continue moving foreward.
Wow! I'm really confused now that I've read my thoughts.
One thing I do know for sure, I think.....
Whether wind blows or sucks is simply a matter of which way I'm facing!