Today we're working on how an airplane creates lift. As pilots, it's really important for us to know how an airplane uses relative winds and the shape of its wings in order to create lift. If you remember from lesson one, lift is that upward force that opposes weight. So how does the airplane create lift? It does it by using Bernoulli's principle. Let's take a closer look. Bernoulli's principle states that as the velocity of a moving fluid increases, the pressure within that fluid decreases. Narrow areas like this, which are often called a Venturi, force the fluid to increase its speed. And with that increase in speed, we get a decrease in pressure. Just like in a Venturi, the curved surface of the upper wing forces the air on top of the wing to travel more quickly than the air on the bottom of the wing. This forces an area of lower pressure on the upper surface of the wing.

So, what happens if there's lower pressure on the upper surface of the wing and higher pressure on the bottom surface of the wing? You get an upward force, and that upward force is known as lift.