photos: Hoh rainforest, 10-11 Sep 2005

[eub]

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That blue Hoh River water -- I don't remember scattering mechanisms. Wikipedia says that glacial rock flour is "grains of a size between 0.002 to 0.00625 mm", 2000 - 6250 nm. I thought you needed to be smaller than the wavelengths of the light if you wanted preferential scattering of high frequencies. Help me out here?

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[beaq.livejournal.com]

Rock flour! I look at it, it mens COLD! Yay! (Perhaps, not, but it has that association for me.)

Might water suspension affect scattering? I speak from ignorance. I will aim laser friend this way, who might also speak from ignorance.

Does everyone take a picture of that spruce? It should charge five bucks a pop.

[hattifattener]

Hm. Yeah, the light will have a different wavelength in water. *scribble scribble* unfortunately, the effect works in the wrong direction: frequency's the same, velocity's slower (N=1.34 or so), so wavelength's shorter (500nm -> 373nm). So the rock flour grains are too small by a factor of several. Some possibilities:

• There's still some preferential scattering, even though the grains are too large; it's just not as strongly preferential as it could be
• There are smaller particles than the flour also in suspension
• Lies, lies, this is all lies. The streams are blue because the mountains scrape off bits of the sky

[hattifattener]

(Er, for "too small by a factor of several" above read "too large…", of course.)