cavelamb wrote:
Ok, so there is a low pressure field above the wing,
and the wing is pressed up from underneath.

So, just out of curiosity, what happens to the air
that was in the low pressure field above the wing -
after the wing passes?

Does it just magically co back to it's old ways
(and places)?

And the air that was in the high pressure field under
the wing?

After the wing passes, is it unaffected as well?

It's all a slowly descending smoke ring. If the earth was "the only
thing that finally stops it" as Alan says, none of the ring's energy
would be lost as it pushes through the surrounding air to reach the earth.

http://www.av8n.com/how/htm/airfoils.html#sec-circulation-vortices
Figure 3.27 ties the wingtip vortices in with the rest of the
circulation pattern, showing the whole smoke ring in red.

Also look up at section Section 3.11,
http://www.av8n.com/how/htm/airfoils.html#sec-spinners
Add the Fluttering Card circulation, Figure 3.25, to familiar tip
vortices, and you get the whole ring.

Other articles do a nice job explaining tip vortices or downwash behind
the wing as isolated subjects, but that's where they end their stories.