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



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

In: Physics

Air bubbles are mixed into the water.

Depending on the temperature of your water from the tap, it will be air and sometimes minerals in the glass.

Super simple version is were seeing bubbles. The water is moving fast and being pushed so it creates bubbles like the top of rapids.

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.

in addition to what the other two said, often there is a small mesh called a [faucet areator](https://en.wikipedia.org/wiki/Faucet_aerator) on the faucet that breaks the flow and incorporates air in it, this creates the white stream of water.

A ‘white’ surface is what we see when all the light hitting something gets bounced back, but scattered in different directions. All other colours are what happens when light hits something, and a little bit gets absorbed.

Water doesn’t absorb a noticeable amount of light. But usually it also doesn’t scatter light – it just lets the light through. However, when light moves from air into water, or the other way around, it bends a little. This is why we can see water even when it’s still.

Water faucets and water falls are mixtures of water and air, with loooots of little bubbles. Every time light moves into or out of one of those tiny bubbles, it gets bent a little. Since there are so many bubbles, a lot of the light ends up scattered back at us, just like a white surface.

As a side note, when light gets bounced back but *not* scattered, you get a reflection.