An aerofoil at a given angle of attack will have what is called a pressure distribution. This pressure distribution is simply the pressure at all points around an aerofoil. Typically, graphs of these distributions are drawn so that negative numbers are higher on the graph, as the for the upper surface of the aerofoil will usually be farther below zero and will hence be the top line on the graph.
Similarly, a pressure distribution can be displayed on the top of the deformed material and locally measured by some microsensor such as a strain gauge or MicroWire.