Water particles loop while the wave shape travels.
The wave shape travels, while water bits mostly loop in place. Those loops reach below the surface.
Tap from deep circular loops to shallow squashed loops.
Tap the same wave at four depths. As the bottom nears, the water loop flattens and the whole wave slows.
Raise the seafloor and measure how the whole wave changes.
deep watershallow water
Matched swells face gentle and steep bottoms without foam.
Same swell, same dry-sand line, two bottom shapes. No wave has broken yet.
Same swell. Same dry-sand line. Two seafloor slopes.
The same swell reaches two beaches. On which beach does it BEGIN breaking farther from dry sand?
Slide both matched swells toward shore.
deep waterbreaking condition
