No, horizontal component of velocity varies around the wing, being quite significantly higher above it than below:
(By Kraaiennest [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], from Wikimedia Commons)
Roughly speaking, without involving math, the behaviour of air is like this:
- The air avoids the leading edge, and due to inertia would like to continue straight away from the wing.
- However viscosity limits the velocity gradient, forcing the air just above and below the wing to move as well¹.
- As the air moves out, it frees up space, so pressure decreases.
- The oncoming air is accelerated along the pressure gradient, which makes it follow the wing contour.
- Decreasing pressure increases velocity due to conservation of energy, as the sum of kinetic and potential¹ energy needs to remain constant; this is known for fluids as the Bernoulli's principle.
- Since the air above the wing has to expand to follow the contour, it has lower pressure and correspondingly higher velocity.
Now in mathematical terms, it is the Navier–Stokes equations. They are set of vector partial differential equations. There is no way to solve them analytically, they can only be integrated numerically with help of suitable software. The basic tool for analysing airfoil shapes, reduced to two dimensions, is XFOIL. There is more complex software that can calculate flow around whole aircraft in three dimensions, but unlike free XFOIL, it is either really expensive, or internal tools of large aircraft manufacturers.
¹ Unless the wing stalls. When the flow has low enough energy, the viscosity is no longer enough to flush out the air above the wing and a pocket of stagnant, and thus higher pressure, air forms above the aft part of the wing, which, since it has higher pressure, no longer pulls the wing up generating lift (some lift is still generated on the underside, but it is much less).
² Well, also thermal energy. In adiabatic expansion, as the pressure decreases, the temperature also decreases, which frees up even a little bit more energy to convert to kinetic, but at typical speeds can be neglected.