When Wind becomes Wind

Why do dogs like to hang their head out the car window, but they hate it when you blow on their face?

I have never met a dog that likes it when you blow on their face. However, most dogs love to hang their head out the window and soak in the sights and smells.

What exactly is the difference?
Is it the smell of our breath that makes it bad?
Is it the velocity? Or, the circumference isn't large enough?
Will we ever know the answer to this most pressing question??

Here's Ms. Jada creating a little wind of her own with some wild-mongoose running:

She makes me smile!