Pressure above the wing is less than atmospheric pressure and pressure below is equal to or more than atmospheric pressure. This corresponds to which angle of attack?

• A. Negative AOA
• B. Zero Lift
• C. Positive AOA
• D. Low Speed

Answer: (C)

When the wing has a positive angle of attack, the airflow is deflected downward more on the bottom and accelerates over the top, producing lower pressure on the upper surface and higher pressure on the lower surface. That suction on top and pressure below is what creates lift. The described pressure pattern—top pressure below atmospheric and bottom pressure at or above atmospheric—matches that lift-producing setup, so it corresponds to a positive angle of attack. A zero lift situation would have nearly equal pressures on both surfaces, and a negative angle of attack would tend to reverse the distribution, reducing lift. Low speed isn’t a defining factor for this pressure distribution.