During a flight at a zero angle of attack, how does the pressure on the upper wing surface compare to atmospheric pressure?

When an aircraft flies at a zero angle of attack, the airflow over the wing is smooth and continuous, allowing for the development of lift primarily due to Bernoulli's principle. This principle states that as the velocity of the airflow over a surface increases, the pressure exerted by that airflow decreases.

In the case of the upper surface of the wing, as air travels faster over it compared to the slower-moving air beneath the wing, the pressure over the upper wing surface becomes lower than the atmospheric pressure. This pressure difference is crucial for generating lift. Therefore, during flight at a zero angle of attack, the pressure on the upper surface of the wing is indeed less than atmospheric pressure, facilitating lift generation and maintaining the aircraft in flight.

This phenomenon explains why the correct choice is that the pressure on the upper wing surface will be less than atmospheric pressure, as it directly relates to the principles of aerodynamics involved in flight mechanics.