A bit of sleuthing on the internet reviewed some great flow, pressure, and velocity distribution animations around wings.  Look at

 

http://www.diam.unige.it/~irro/profilo_e.html

 

 

You can read the text (dry) or go directly to the bottom of the page for small panels you can click on to see the various displays.  Work from left to right.  Definitely worth doing. 

 

Totally cool and highly educational.  Keep watching closely as the angle of attack is changed.  Note that this airfoil is concave down on the bottom to exaggerate the visualization.  Our wings are convex down on the bottom, and actually have negative pressure on bottom and top, compared to the free stream static pressure.  This changes the local pressure field around the bottom of the wing (helps laminar flow), but farther from the bottom of the wing the pressure goes positive.  But I digress again….

 

Note in particular how the atmosphere is distorted by the passage of a wing as shown in the panel presenting streak lines.  The flow is actually sheared and displaced by the passage of the wing.

 

 

 Note also the pressure field which shows why there is such strong upwash in front of the wing: high pressure below and in front of the wing, and low pressure above and in front of the wing.  It makes those funny inboard leading edge slats on the B727 a bit more comprehensible. 

 

 

 

Enjoy,

 

Fred