Why Is the Foam on a Dark Drink White?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why is the foam on a dark drink white?

The Big Idea

Foam is made of many tiny bubbles, each with a very thin skin of liquid. Light bounces off all those skins in every direction, and none of it gets absorbed before it comes back out. So the foam looks white, even when the drink under it is dark.

Tiny Bubbles

Step one: tiny bubbles. Foam is a froth of countless air pockets, packed close together. Each pocket has a thin skin of liquid around it.

Scattered Light

Step two: scattered light. Light bounces off the skin of every bubble. With so many skins, it bounces again and again in new directions.

No Time to Absorb

Step three: no time to absorb. The light does not travel far through the dark liquid. So all colors return to your eyes together, and you see white.

A Closer Look

Let's take a closer look! The drink underneath is dark. The foam is made of bubbles. Together, they look white. White ocean waves work the same way, and so does the frothy top of a milkshake.

Quick Facts

Quick facts! The same trick turns clear water into white waves and white clouds. Soap suds in the sink look white too, even in dirty dishwater. Tiny bubbles are the reason, not the color of the liquid. Blow, don't suck, when making bubbles with a straw.

Think Like a Scientist

Now, think like a scientist! Pour some dark juice into a glass. With a grown-up's help, blow bubbles into it with a straw. Blow, don't suck. Look at the white foam on top. What color is the liquid underneath?

Outro

Many tiny bubbles scatter light, so foam looks white. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!