Why is Snow White Instead of Clear Like Ice?

[pivoxa15]

Ice cubes do not have a colour but snow (which is claimed to be frozen water or ice) is white. Why?

 

[lalbatros]

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

 

[Mickey]

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.

 

[HallsofIvy]

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?

 

[Farsight]

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.

 

[Danger]

Why is snow white?

Because she makes the dwarves shower first.[/color]

Sorry, mentors. Feel free to delete it, but I just couldn't let that go by.

 

[pivoxa15]

"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.

 

[Cyrus]

Haven't you seen the inside of a freezer?

 

[pivoxa15]

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 doesn't appear in the dictionary http://en.wiktionary.org/wiki/Special:Search?search=facettes&go=Go

 

[pivoxa15]

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.

 

[Danger]

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.

 

[Gokul43201]

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).

 

[Farsight]

Sorry, wrong thread, post deleted.

 

[pivoxa15]

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?

 

[Triss]

Could you give me a link to it?

https://www.physicsforums.com/showpost.php?p=899393&postcount=4

 

[pivoxa15]

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?

 

[russ_watters]

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.

 

[pivoxa15]

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).

 

[Danger]

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).

 

[russ_watters]

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.

 

[Danger]

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.

 

[keinve]

White is not a color.

yes, white is a color. you are somehow confusing 'white' with 'clear'.

 

[Rahmuss]

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.

 

[jobyts]

What's the difference between snow and ice? Is snow a stage in between water and ice?

 

[russ_watters]

Snow is ice.

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