Why Are Birds Able to Fly?

The most important reason is the aerodynamic buoyancy!

When the air hits the wing, it is split upwards and downwards. Since the wings are curved, the upper part of the air has to cover a longer distance. In order to be on time to meet the air from the bottom side, which flows without any detours, the air from the top side has to flow faster. Underneath the wing, the flow rate of the air is slower. These circumstances lead to pressure differences.

At the top, a negative pressure is generated. At the bottom there is an excess pressure. The bird is "pushed up" from below and "raised" from above.