Well, it spoils the joke but Okay:
https://en.wikipedia.org/wiki/Ground...(aerodynamics)
If a cars attitude is nose up so there is a positive pressure underneath, it approaches ground effect. It's exploited the most in the
Ekranoplan type airframe.
The joke is that it's really
https://en.wikipedia.org/wiki/Microscale_meteorology AKA ground turbulence.
Quote:
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Flow over a golf ball. (This can be best understood by considering the golf ball to be stationary, with air flowing over it.) If the golf ball were smooth, the boundary layer flow over the front of the sphere would be laminar at typical conditions. However, the boundary layer would separate early, as the pressure gradient switched from favorable (pressure decreasing in the flow direction) to unfavorable (pressure increasing in the flow direction), creating a large region of low pressure behind the ball that creates high form drag. To prevent this from happening, the surface is dimpled to perturb the boundary layer and promote transition to turbulence. This results in higher skin friction, but moves the point of boundary layer separation further along, resulting in lower form drag and lower overall drag.
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