water is transparent right, so when we put on the tap or see a waterfall, it turns white, why is that?

Question

water is transparent right, so when we put on the tap or see a waterfall, it turns white, why is that?

In: Physics

Answer 1

Air bubbles and turbulence. When the Reynolds number (density * volumetric flow rate * characteristic length / viscosity) of water reaches a certain number (over 10,000), the water molecules move about in a chaotic fashion, so you can’t see through it. Reduce the density, flow rate or characteristic length, or increase the characteristic length, and you’ll see [laminar flow](https://youtu.be/ElYF5pl-pYY), which is how you expect it to act.