I've known this fact for a long time and have thought about an explanation for it for just as long. I've observed its effects such as in the shower: as the water flows down it moves the air with it causing the curtain to move inward into the shower. It just seems that with a moving fluid that, if anything, it would create a higher pressure and push things outward. I cannot come up with an explanation with my intuition so I'm asking for one. What is the physical explanation for moving fluids having lower pressures?