This is a fun animation which shows all the forces acting on a skydiver, check it out in motion at this site!
Here is a link to an extreme skydiver
If you wanted to calculate this terminal velocity all you would need to do is set the drag force equal to the force of gravity and solve for v.
Because air density increases with decreasing altitude, this causes an increased buoyant force near the surface of the earth. The buoyant force causes the terminal velocity to decrease by 1% every 525ft.
The world record for skydiving speed of 614 mph was obtained at high altitude where the less dense air reduces drag and buoyant effects.