Why are clouds white?

[Dorfl]

I'm still trying to figure out why Dorfl thinks that ice is blue ....

From Ask a Scientist, http://www.newton.dep.anl.gov/askasci/gen01/gen01514.htm:

Large blocks of ice absorb light from the visible spectrum, preferentially absorbing from the red end of the spectrum so thicker volumes of ice will let blue light through. Thus the ice will have the color blue. Also, the purer the water that is used in making the ice, the more pronounced the blue color will be. Man- made artificial ice will not be as bluish in color because of impurities. I hope that this is helpful.

Admittedly, the answers on that page do not quite agree with each other. Some of them claim that the color is due to scattering, and not absorbtion:

Ice is colorless in that it does not absorb any visible light; however, thick slabs of ice like liquid water can scatter light giving it a bluish cast.

But either way, a large slab of ice will look blue.

 

[Paulhoff]

It's not?!

Is there any short explanation for why the sky is still blue, or should I start a second thread about that?

It is mainly because of dust in the air. A lot of the dust is small enough that longer wavelengths of light, at the red end of the spectrum, aren't reflected but go around the dust but the shorter wavelengths like blue are and comes to you eyes.

Paul

 

[rjh01]

To add to post 42 the red light is not scattered so much so you get a red sunset and sunrise.

 

[CaveDave]

Math geeks alert!!

Funny, that is the introduction of 'The cuckoo egg' by Mr. Clifford Stoll.

He states that to explain that, you will go into the frequencies of light and into subatomic reasoning as well...

(yeah, I know, there is no such thing as 'subatomic reasoning', but... meh!)

LOVED that book! (must have read it about 20 years ago - before the public had heard of the Internet)

Have you seen his current endeavor, Acme Klein Bottle? Hilarious stuff, there. Educational even if you don't want to be.

Check out the "Portraits of Gauss" and Cup of Tantalus. Hell, read it all, even the "boring" FAQ; that guy has a great sense of humor.

And then, here find a
Photo of Cliff with his masterpiece. Bet that babe masses a kg or three!

Cheers,

Dave