Picture 2: source.
Consider I have an airplane and it wing, of course. The cross-section of the airfoil is as the picture 1. The leading edge and the wind direction are depicted there. The leading edge I depicted as simple as possible to make it easy to be understood. It is exactly a half of a circle. For clearer, you may see the second picture or watch the video of the link I provided above.
Then my question is, how do I calculate the air pressure in the leading edge's top bulge as in the first picture?