Lift is the aerodynamic force component perpendicular to the freestream. On an airfoil, it comes mainly from integrating surface pressure (with a smaller viscous contribution to the overall force balance).
01
Pressure difference
At positive alpha (or with camber), average upper-surface pressure is typically lower than the lower surface — that net Δp produces lift.
02
Angle of attack
Raising alpha usually raises Cl until separation grows and the section stalls. That is why Cl–α is the first polar to learn.
03
Circulation idea (optional)
Classical theory also describes lift with circulation around the section. Useful later — not required on day one.
Image placeholder — Cp plot at two alphas
What lift is not
- Not “molecules racing and meeting at the trailing edge at the same time”
- Not only “Bernoulli on top, nothing on the bottom”
- Not independent of Reynolds number in the real world
Related: What Is an Airfoil? · Reading Cp Plots