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Author Topic: Why is Snow White and Glaciers Blue ?  (Read 9164 times)

Offline neilep

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Why is Snow White and Glaciers Blue ?
« on: 26/11/2005 20:09:57 »
I've never really thought about this ....until now....... but why is the snow in my freezer white  and glaciers blue ?...is it a light refraction thing happenning here ?

ta



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Offline ukmicky

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Re: Why is Snow White and Glaciers Blue ?
« Reply #1 on: 27/11/2005 05:07:15 »
Are glaciers blue i always thought they were white.:)

Ok i actually know this, its because the red part of the spectrum is absorbed by  the ice but the blue part which is a shorter wavelength isnt and is transmitted through the ice and scattered ,  the thicker the glacier the more red is absorbed making it appear more blue  
With snow as you see white i take it the red wavelenght isnt absorbed much and is mostly scatered back to your eyes with the blue.

as its late my explanation  maynot be to good. but you should get what i mean

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Offline daveshorts

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Re: Why is Snow White and Glaciers Blue ?
« Reply #2 on: 27/11/2005 12:55:33 »
The ice in the snow is in  much smaller lumps than that of the glacier so the light will get refracted in random directions and most of it will eventually bounce out again, so it looks white. In the Glacier the light refracts less often so the light will pass through more ice before it escapes again, so any weak colour in the ice will be a lot more obvious.
 

Offline neilep

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Re: Why is Snow White and Glaciers Blue ?
« Reply #3 on: 27/11/2005 18:25:58 »
Thank you Michael and thank you Dave.....query resolved..cheers.

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Offline DoctorBeaver

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Re: Why is Snow White and Glaciers Blue ?
« Reply #4 on: 27/11/2005 23:22:58 »
The only glacier I've seen was white
 

Offline neilep

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Re: Why is Snow White and Glaciers Blue ?
« Reply #5 on: 28/11/2005 00:14:02 »






Not any more Eth :D

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Offline DoctorBeaver

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Re: Why is Snow White and Glaciers Blue ?
« Reply #6 on: 29/11/2005 15:11:17 »
OOOH![:p]

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Offline Bass

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Re: Why is Snow White and Glaciers Blue ?
« Reply #7 on: 30/11/2005 21:00:26 »
Have you also noticed that the lakes and rivers below glaciers are turquoise blue?

Moraine Lake, Banff Nat'l Park, Canada


The silt from the glacial ice causes reftraction- absorbing more of the red/yellow spectrum than the blue/green.  I wonder if the silt in the ice is also partly responsible for the blue color of glaciers.

I got some silt out of my garden and mixed it in a glass of water today.  When I put it outside (-9C) it was brown, and when frozen the ice was still brown.  Maybe the glass wasn't large enough?

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sharkeyandgeorge

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Re: Why is Snow White and Glaciers Blue ?
« Reply #8 on: 10/12/2005 14:39:18 »
neilep your first pic was so beutiful i want it for my wallpaper

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sharkeyandgeorge

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Re: Why is Snow White and Glaciers Blue ?
« Reply #9 on: 10/12/2005 14:41:31 »
well its done but not so beutiful in strech where can i get the origional high res?

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Offline neilep

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Re: Why is Snow White and Glaciers Blue ?
« Reply #10 on: 10/12/2005 22:03:03 »
I love that piccy too, it's full of blue ice love...and as an added bonus it has penguins too !!!..honestly what more could you want on a Saturday night ?

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another_someone

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Re: Why is Snow White and Glaciers Blue ?
« Reply #11 on: 10/12/2005 22:31:40 »
Apart from what has been mentioned about the structure of the ice, also I suspect the colour of illumination under which you viewed the ice in your fridge was different to the colour of illumination under which you viewed the glacier.
 

Offline neilep

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Re: Why is Snow White and Glaciers Blue ?
« Reply #12 on: 10/12/2005 22:46:28 »
quote:
Originally posted by another_someone

Apart from what has been mentioned about the structure of the ice, also I suspect the colour of illumination under which you viewed the ice in your fridge was different to the colour of illumination under which you viewed the glacier.



Agreed !..though, it was my freezer, not my fridge !:D

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Offline chris

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Re: Why is Snow White and Glaciers Blue ?
« Reply #13 on: 11/12/2005 22:01:45 »
Great question

The reason for this interesting observation is that white snow is reflecting all of the incident light back at you, and absorbing just a little bit. That's because snow comprises lots of tiny crystals, the surfaces of which all behave like tiny mirrors.

But in well-packed ice the crystals are much larger and the light hitting the ice penetrates some distance before bouncing back off a fault or a crystal surface.

So why is it blue ? Well, water absorbs wavelengths of light at the red end of the spectrum, leaving bluer (shorter) wavelengths untouched. This is why the underwater scene looks very blue if you go diving (without supplemental light) - because as the sunlight filters down through the water, progressively more long (red) wavelengths are removed, giving the surroundings a blue hue.

Exactly the same is true with ice. As the light penetrates the ice the red wavelengths are removed, leaving a blue-dominated spectrum behind. Since, compared with snow, the light has to travel further inside the ice before it is reflected, the effect is exaggerated and you see blue ice.

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Re: Why is Snow White and Glaciers Blue ?
« Reply #13 on: 11/12/2005 22:01:45 »

 

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