My understanding of suction is that it is a phenomenon describing the flow of fluid from a (relatively) high pressure volume into a (relatively) low pressure volume. This makes sense to me, as I grasp that air pressure is a measurement that describes a large number of molecules, each with its own momentum, and that the higher the mean momentum, the higher the air pressure. Accordingly, when you introduce a volume that has a relatively low air pressure relative to its surrounding volume, and there is no barrier between these two volumes, the molecules in the higher pressure system will tend to distribute themselves to fill in the "gap". To me, this is statistically similar to the phenomenon of increasing the homogeneity of a cake batter by stirring it enough. What I'm having difficulty understanding is how a vacuum cleaner is able to generate so much suction. My understanding is that the maximum suction is a function of the difference in air pressure between the two "volumes". Even if a vacuum cleaner creates a perfect vacuum internally, surely the amount of suction force is limited by the air pressure of the environment "outside" the vacuum cleaner. It also would seem that the area of the channel connecting the vacuum to the outside world plays an important role, similarly to how pressure is a function of the area over which a force is distributed. Perhaps the length of the channel also plays a role, but this is more speculative on my part. So here are some questions to test my understanding: 1: Suppose you have a constant "external" air pressure, and you're using a vacuum pipe with a fixed diameter and length. Will the maximum suction physically possible be experienced when a perfect vacuum is created inside the cleaner? 2: Are there any other sort of mechanisms that can provide for even greater amounts of suction than that referenced in question 1? 3: What is a useful way of formally quantifying "suction"? thanks!