Definition
A principle of fluid dynamics stating that within a steady flow of air or fluid, an increase in the speed of the flow is accompanied by a decrease in its static pressure, and a decrease in speed is accompanied by an increase in pressure. In aviation, this principle helps explain how a difference in pressure between the upper and lower surfaces of an airfoil contributes to the production of lift.
Plain English
When air speeds up, its pressure drops; when it slows down, its pressure rises. On a wing, air moving faster across the top has lower pressure than the slower-moving air underneath, and that pressure difference helps lift the wing.
Context Anchor
Seen in basic aerodynamics when studying how airflow around a wing helps create lift.
Derivation
Named after Daniel Bernoulli, an 18th-century Swiss mathematician who described the relationship between fluid speed and pressure. 'Differential' simply means 'a difference between' — here, the difference in pressure between two regions of moving air.
Why Pilots Care
It explains how wings produce most of their lift through pressure differences, directly affecting takeoff, climb, and stall behavior.
Analogy
Think of squeezing a garden hose. The water speeds up where the hose narrows — and at that fast-moving point, the water exerts less sideways pressure on the hose walls than it does in the wider, slower sections.
Grounding Statement
Picture air moving faster over one part of a wing and slower over another; the faster side has lower pressure, so the pressures are not balanced.
Intuition Check
Do not read this as “faster air always means more lift by itself.” The key idea is lower pressure in faster flow, and the pressure difference can contribute to lift.
Example Sentence 1
The instructor explained that Bernoulli's Principle of Differential Pressure accounts for the lower pressure on top of the wing, which combines with the higher pressure underneath to produce lift.
Example Sentence 2
During preflight planning the student recalled that Bernoulli's Principle of Differential Pressure still applies even when the wing is at a low angle of attack.