Air flows from left to right past an aerofoil. Three steps. Step 1, Bernoulli: air over the curved upper surface moves faster than air under the flatter lower surface, so the dots above pull ahead of the dots below. Faster air has lower pressure: a low pressure region above and a high pressure region below give an upward force, lift. Step 2, Coanda: the air next to the upper surface follows the curve instead of going straight, and leaves the trailing edge turned downward. Step 3, Newton's third law: the aerofoil pushes air down (action), and the air pushes the aerofoil up (reaction), which is lift. All three work together; no single principle explains lift on its own. The flow is schematic, not measured. The still frame shows step 3.
