Airplanes: Explaining pressure differences

Most aeroplane wings are curved on the upper surface and flatter on the lower surface, making a sectional shape, named an airfoil.

• As a curved airfoil wing flies through the sky, it deflects the air and changes the air pressure above and below it.
• The air pressure changes because the air that flows over the curved upper surface wants to move in a straight line, but the curve pulls the air around and back down, causing the air to stretch out into a bigger volume, lowering the pressure.
• The pressure of the air under the wing increases for the opposite reason.
• The difference in air pressure between the upper and lower surfaces causes a difference in air speed. When they arrive at the tail end of the wing, the molecules of both will be speeding downward, producing lift.