Why are snow and hail white?

Question

They're made from water, which is colorless. If precipitation falls as rain, it's colorless. When a snowball or hailstone melts, it's colorless. Ice cubes, assuming no outside pollutants, are colorless. So how does a colorless liquid become white when it falls frozen from the sky?

Answer 1

the unthinking majority will never know this answer... I've always thought it was God's wild dandruff problem but now I'm not sure. He's been given endless bottles of head and shoulders and doesn't have a dandruff problem anymore.  

Answer 2

In short, it's because the ice crystals in snow and hail are not aligned, and therefore they refract light in all directions. Individual ice crystals are translucent, but when clumped into snow flakes or hailstones (which also have air trapped in them), you get a structure that appears white.

Answer 3

if you look at indivudial snow flakes it is clear, but the bits of ice reflect the sky and white light making it white when there is lots of it together.

Answer 4

I think it's because of the ice crystals that form and the way the reflect light. You've seen clear parts of ice cubes, too - it is frozen at a steady temp where crystals don't form.

Answer 5

Of course it's white. Could you imagine if it was chartreuse?

We would have Snow Chartreuse and the seven dwarfs,and winter would look really really funny, you couldn't tell people not to eat the yellow snow because it would ALL look yellow!

Seriously now, what were you thinking?

Answer 6

I was just checking so see how Chacha would dirty this one up. Wow, curve ball.

Answer 7

Ya brah, why's it gotta be white?  Thats green brah thats green.

Answer 8

To understand where the whiteness comes from, we need to back up and look at why different things have different colors in the first place. Visible light is made up of many different frequencies of light. Our eyes detect different frequencies as different colors. Different objects have different colors because the particular particles (atoms and molecules) that make up the object have different vibration frequencies. Basically, the electrons of the particle will vibrate a certain amount in response to energy, depending on the frequency of the energy. In the case of light energy, the molecules and atoms absorb a certain amount of light energy depending on the frequency of the light, and then emit this absorbed energy as heat. This means that objects absorb certain frequencies of light more than others.

A couple of different things can happen to the light frequencies that are not absorbed. In some material, when a particle re-emits the photons, they continue to pass through to the next particle. In this case, light travels all the way through the material, so the material is clear. In most solid material, the particles re-emit most of the unabsorbed photons out of the material, so no light, or very little light, passes through and the object is opaque. The color of an opaque object is just the combination of the light energy that the object's particles did not absorb.

So, since snow is frozen water, and we all know that frozen water is clear, why does snow have a distinctive color? To understand this, we need to back up and look at an individual piece of ice. Ice is not transparent; it's actually translucent. This means that the light photons don't pass right through the material in a direct path -- the material's particles change the light's direction. This happens because the distances between some atoms in the ice's molecular structure are close to the height of light wavelengths, which means the light photons will interact with the structures. The result is that the light photon's path is altered and it exits the ice in a different direction than it entered the ice.

Snow is a whole bunch of individual ice crystals arranged together. When a light photon enters a layer of snow, it goes through an ice crystal on the top, which changes its direction slightly and sends it on to a new ice crystal, which does the same thing. Basically, all the crystals bounce the light all around so that it comes right back out of the snow pile. It does the same thing to all the different light frequencies, so all colors of light are bounced back out. The "color" of all the frequencies in the visible spectrum combined in equal measure is white, so this is the color we see in snow, while it's not the color we see in the individual ice crystals that form snow.