Pression atmosphérique vs. pression d'air
In French, 'pression atmosphérique' and 'pression d'air' both refer to the concept of air pressure, but are used in slightly different contexts.
Pression atmosphérique
This term refers to the weight of the atmosphere as it presses down on the Earth's surface. It is a specific term used in meteorology and related sciences to discuss weather patterns, altitude effects, and more.
La pression atmosphérique diminue avec l'altitude.
(Atmospheric pressure decreases with altitude.)
Un baromètre est un instrument qui mesure la pression atmosphérique.
(A barometer is an instrument that measures atmospheric pressure.)
Pression d'air
While also related to the force exerted by air, this term is more generic and can be applied in a broader range of contexts, including engineering, physics, and everyday situations where air pressure is a factor.
La pression d'air dans les pneus doit être vérifiée régulièrement.
(The air pressure in the tires must be checked regularly.)
Une fuite dans le système peut causer une baisse de la pression d'air.
(A leak in the system can cause a drop in air pressure.)
Summary
'Pression atmosphérique' and 'pression d'air' both refer to air pressure, but they differ in their usage context. 'Pression atmosphérique' is used specifically to discuss atmospheric conditions that are important in meteorology and science, while 'pression d'air' has a broader application, covering any situation where air pressure is relevant.