Plain English Meaning
When air or any fluid speeds up, its pressure drops. When it slows down, its pressure rises.
Full Definition
A principle of fluid dynamics stating that as the speed of a moving fluid (liquid or gas) increases, the pressure within that fluid decreases. In aviation, this relationship between velocity and pressure helps explain how airflow over a wing produces lift and how venturi-style devices generate suction for pneumatic instruments.
Context Anchor
Seen in pneumatic system discussions, especially when explaining how airflow or a venturi-type passage can create the pressure difference used by gyroscopic instruments.
Derivation
Named after Daniel Bernoulli, an 18th-century Swiss mathematician who described the relationship between fluid speed and pressure. Knowing it is a person's name (not a technical word) helps avoid trying to decode the term itself.
Why Pilots Care
It explains how venturis generate the vacuum that spins attitude and heading indicators when engine-driven pumps are unavailable.
Analogy
Think of a garden hose. When you squeeze the nozzle, the water speeds up as it passes through the narrow opening. In the same way, air speeding up over a curved wing surface has lower pressure than the slower air beneath it.
Grounding Statement
Faster-moving air pushes sideways with less force than slower-moving air.
Intuition Check
Do not think “faster air” means “more pressure” in this context. Here, faster airflow means lower static pressure, which can create a useful pressure difference.
Example Sentence 1
Bernoulli's principle helps explain why the lower pressure above a wing, where air moves faster, produces lift.
Example Sentence 2
During preflight the pilot checks that the suction gauge shows proper vacuum created by Bernoulli's principle in the pneumatic system.