Why is snow white?

Question

I know that this is a rather ambiguous question; but my question is, whenever we take water and freeze it in the freezer, it still tends to stay clear. Since snow is just frozen water, why is it white? Is it due to contents of the air - i.e. dust - that make snow this color?

Or is my freezer just weird?

Because the "color" is a description of frequency. Snow reflects a combination of frequencies of light, and their sum is turning out to be white. — M.A.R., Feb 28 '15 at 18:35
Ok well then what makes this reflect this "combination" and normal ice cubes don't tend to do that? — Asker123, Feb 28 '15 at 18:35
Translucent but not completely white right? So why even an individual snowflake appear white? — Asker123, Feb 28 '15 at 18:39
[This](http://en.wikipedia.org/wiki/Snowflake) might be of interest. — M.A.R., Feb 28 '15 at 18:41

score 33 · Accepted Answer · answered Feb 28 '15 at 18:49

The difference between snow and ordinary ice cubes is mainly about the size of the particles. Snow is made from small, irregular crystals with many edges at a very small scale. Light is refracted or scattered by the edges (or the interface between air and the edges). Snow is white because the scattering effect of those edges dominates what happens to light shining on the snow. In a large block of ice like an ice cube there is very little refraction or scattering as, for any ray of light, there are only two edges (one when light enters the cube, one when it leaves). So transmission dominates (and there is little colour as ice only weakly absorbs visible light).

This is common in many other compounds. Titanium dioxide is a transparent mineral but is used as the primary ingredient in many "white" products like paint. The secret is to use TiO₂ particles that are just the right size to maximise the scattering at the particle edges thereby creating "whiteness" as all light is equally scattered.

score 5 · Answer 2 · answered Mar 01 '15 at 04:57

As matt_black said, it's about the size. If you take a tall, thick glass tube, it'll be transparent, right? It'll transmit the light falling on it. But make it thinner and thinner(think human hair) then it'll appear white, as it'll refract the light passing through it. As the light from the sun(which is a combination of all colors) is white, snow appears white.

Many people think that old people's hair are white, but they're not. They get their color(black, brown, yellow, red, whatever) from a pigment called melanin, and in white hair this pigment is absent, leaving only a transparent rod of hair. It's so small it appears white.

About the ice cube part, if you've observed, sometimes there's a ice cube that's transparent on the outside, but in the middle there's a white core. That happens because it has shattered in the middle, probably because of anomalous expansion of water.

Why is snow white?

2 Answers2

Linked