aerodynamics,
Try this, open the passenger rear window, next open the sunroof... The air will come in got to the back of the vehicle, make its way back up to the drivers side and to the drivers seat area and go out the sunroof.. your passenger will not feel any air...
Next reverse the two rear windows, close the passenger rear side window open the Drivers side rear window, you the driver will not feel anything, but look over at you girl next to you in the passenger seat and see her hair flying all over the place...
Then close the sunroof & you will hear two things.. 1st the thumping from the air, as described in the first post... 2nd the thumping your getting from your girlfriend as she hits you for messing up her hair.....