Why is Snow White? Exploring Color in Ice

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In summary, ice cubes do not have a color because they have a small number of facets that reflect light, making them appear transparent. However, snow has millions of facets that reflect light a million times more, causing it to appear white. This is due to the powder structure of ice, which also causes light to diffuse and make transparent materials, like glass and sand, appear whiter and brighter when crushed. The same concept applies to white cement, which appears brighter when ground finer. This explanation can be found in post#4 of the Physics FAQ, and it highlights the different ways light interacts with ice and snow, even though they are made of the same atoms.
  • #1
pivoxa15
2,255
1
Ice cubes do not have a colour but snow (which is claimed to be frozen water or ice) is white. Why?
 
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  • #2
Snow crystals have many facettes.
Each facette reflect a small part of the light.
An ice cube basically shows two facettes. You can observe easily that each do reflect some light.
Consider now the same volume of ice. The physical properties are the same (refractive index is the same) but you have maybe millions of facettes and the reflection is then a million times larger. The reflexion can become so large that in the end snow looses transparency and attenuate light quite a lot. The theory is a little bit more complicated because of multiple reflexions and attenuation, but the principles remain.

Another effect of the powder structure of ice is the diffusion of light.

You can observe the same effect on any transparent material, like glass or even sand.
Crush it fine and it will look whiter and brighter. Whitheness and brightness is something to be discussed also in more detail: take a book on color perception or colorimetry.

White cement (prepared with whiter raw materials) appears brighter when it is grinded finer.

Michel
 
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  • #3
Actually, ice cubes will also have a white color if the water freezes quickly and has impurities in it. The impurities contribute to irregularities in the crystal structure and make thousands of little bubbles.

If the water freezes slowly, however, then the impurities are more likely to fall away from the crystalline structure, and you will have clear ice.
 
  • #4
pivoxa15 said:
Ice cubes do not have a colour but snow (which is claimed to be frozen water or ice) is white. Why?
"claimed to be" ? Do you doubt that? Have you ever carried a handful of snow into the house? What happened?
 
  • #5
pivoxa15 said:
Ice cubes do not have a colour but snow (which is claimed to be frozen water or ice) is white. Why?
White is not a color. So snow doesn't have a color either. :smile:
 
  • #6
Why is snow white?
Because she makes the dwarves shower first. :uhh:

Sorry, mentors. Feel free to delete it, but I just couldn't let that go by. :redface:
 
  • #7
HallsofIvy said:
"claimed to be" ? Do you doubt that? Have you ever carried a handful of snow into the house? What happened?

I should have mentioned that I have never had the opportunity to touch snow before because I have never been to a place that has snow.
 
  • #8
Haven't you seen the inside of a freezer?
 
  • #9
lalbatros said:
Snow crystals have many facettes.
Each facette reflect a small part of the light.
An ice cube basically shows two facettes. You can observe easily that each do reflect some light.
Consider now the same volume of ice. The physical properties are the same (refractive index is the same) but you have maybe millions of facettes and the reflection is then a million times larger. The reflexion can become so large that in the end snow looses transparency and attenuate light quite a lot. The theory is a little bit more complicated because of multiple reflexions and attenuation, but the principles remain.

Another effect of the powder structure of ice is the diffusion of light.

You can observe the same effect on any transparent material, like glass or even sand.
Crush it fine and it will look whiter and brighter. Whitheness and brightness is something to be discussed also in more detail: take a book on color perception or colorimetry.

White cement (prepared with whiter raw materials) appears brighter when it is grinded finer.

Michel

Could you say more specifically what you mean by 'facettes'? Is this a proper word because it dosen't appear in the dictionary http://en.wiktionary.org/wiki/Special:Search?search=facettes&go=Go
 
  • #10
cyrusabdollahi said:
Haven't you seen the inside of a freezer?

Good one. I have seen the frost in my fridge and I can remember that it is white. But would you call it snow? Altough they are very related, if not the same. I'd rank from most to least transparent ice cube, frost, snow.
 
  • #11
Pivoxa, it's spelled 'facets' in English. It simply means 'faces', as in the flat bits on a diamond.
If you shave an ice cube, or put some of that frost in a blender for a while, you'll have snow. You can surprise someone with a snowball upside the head. :devil:
 
  • #12
pivoxa15 said:
Ice cubes do not have a colour but snow (which is claimed to be frozen water or ice) is white. Why?
The answer is in post#4 of the Physics FAQ (particularly in the moral at the end).
 
  • #13
Sorry, wrong thread, post deleted.
 
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  • #14
Gokul43201 said:
The answer is in post#4 of the Physics FAQ (particularly in the moral at the end).

Could you give me a link to it?
 
  • #15
pivoxa15 said:
Could you give me a link to it?

https://www.physicsforums.com/showpost.php?p=899393&postcount=4 [Broken]
 
Last edited by a moderator:
  • #16
lalbatros said:
Snow crystals have many facettes.
Each facette reflect a small part of the light.
An ice cube basically shows two facettes. You can observe easily that each do reflect some light.
Consider now the same volume of ice. The physical properties are the same (refractive index is the same) but you have maybe millions of facettes and the reflection is then a million times larger. The reflexion can become so large that in the end snow looses transparency and attenuate light quite a lot. The theory is a little bit more complicated because of multiple reflexions and attenuation, but the principles remain.

Another effect of the powder structure of ice is the diffusion of light.

You can observe the same effect on any transparent material, like glass or even sand.
Crush it fine and it will look whiter and brighter. Whitheness and brightness is something to be discussed also in more detail: take a book on color perception or colorimetry.

White cement (prepared with whiter raw materials) appears brighter when it is grinded finer.

Michel

This explanation is pretty much what is contained in post#4 of the Physics FAQ except in less technical detail and applied specifically to ice and snow. The collective behaviour of ice cube and ice snow are slightly different and so light interacts with them slightly differently, even though they are made out of the same combination of atoms.

Could you take a little bit of snow and make it so it has the physical features of ice again i.e. become more transparent?
 
  • #17
pivoxa15 said:
Could you take a little bit of snow and make it so it has the physical features of ice again i.e. become more transparent?
Sure, you could rearrange the crystal structure by releasing and reforming the bonds that hold the water molecules in place.

In other words, melt it and re-freeze it.
 
  • #18
russ_watters said:
Sure, you could rearrange the crystal structure by releasing and reforming the bonds that hold the water molecules in place.

In other words, melt it and re-freeze it.

You would assume that the way water was fozen in the atomsphere is different to the re-freeze (i.e. done in the fridge)? Hence get different structures the second time round (i.e. more ordered structures).
 
  • #19
Pivoxa, the pressure inside of a refrigerator is exactly the same as that outside of it. It's not air-tight to that extent (which is not to say that it would make a good play-pen).
 
  • #20
pivoxa15 said:
You would assume that the way water was fozen in the atomsphere is different to the re-freeze (i.e. done in the fridge)? Hence get different structures the second time round (i.e. more ordered structures).
Absolutely. When it forms in the atmosphere, it is suspended in the air.
 
  • #21
Sorry, pivoxa... I misinterpreted your question. I thought that you meant that an ice cube formed by putting the tray outside in winter would be at a different ambient pressure than one done in your freezer. High-elevation formation, though, is definitely different than that at sea level.
 
  • #22
Farsight said:
White is not a color.

yes, white is a color. you are somehow confusing 'white' with 'clear'.
 
  • #23
Do a search online for images of icecubes and you'll see most of them have white light reflected from them. There are also darker areas because of what's shining through from what they're sitting on. But if you stacked them up more and more and more (millions of tiny icecubes) and you looked at it from a distance, it would look largly just white.
 
  • #24
What's the difference between snow and ice? Is snow a stage in between water and ice?
 
  • #25
Snow is ice.

Please note, this thread is more than a year old. There is no point in replying to year-old posts.
 

1. Why is snow white?

Snow appears white because it reflects all colors of the visible spectrum. This means that when sunlight or artificial light hits a snowflake, it bounces off and reflects back to our eyes as white light, making the snow appear white.

2. Is snow really colorless?

Technically, snow is not completely colorless. Snowflakes are actually made up of water molecules that have a slight blue tint, but when light is reflected off of them, the combination of all colors creates the appearance of white.

3. How does the color of snow change?

The color of snow can change based on certain factors such as pollution, dust, and temperature. Pollution and dust particles can get trapped in snow, giving it a gray or dirty appearance. Temperature can also affect the color of snow, as warmer temperatures can cause the snow to melt and refreeze, altering its appearance.

4. Why does snow sometimes appear blue or pink?

Under certain lighting conditions, snow can appear to have a blue or pink tint. This is due to a phenomenon called "albedo," where the color of an object is affected by the color of the light source. When snow is illuminated by a blue or pink light source, it can take on those colors.

5. How does exploring the color of ice help us understand the world around us?

Studying the color of snow and ice can give us insights into various natural processes and phenomena, such as the effects of pollution and climate change on the environment. Additionally, understanding the science behind color in ice can help us develop new technologies and materials, as well as improve our understanding of light and color in general.

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