Sunday, August 3, 2008

Color in Mountain Streams

While I was painting this 11x14 inch plein air study of Esopus Creek, I was thinking of a quote by John Ruskin’s (from The Elements of Drawing).

He said that he likes to paint

“mountain streams when the water is shallow, and the tones at the bottom are rich reddish-orange and black, and the water is seen at an angle which exactly divides the visible colors between those of the stones and that of the sky, and the sky is of clear, full, blue. The resulting purple, obtained by the blending of the blue and the orange-red, broken by the play of innumerable gradations in the stones, is indescribably lovely.”

I don’t know if I succeeded in capturing what he was talking about, but he sure has a wonderful way of describing the colors of mountain streams. I’ve noticed that when you look at a stream with gray stones and clear water on a sunny day, there’s far more color beneath the surface of the water than above it.

What I’ve been trying to understand, and am still grappling with (maybe you can help me), is why the stones on a shallow bottom of the stream shift to warm, brownish colors, and then the colors get progressively cooler as you go deeper than about three feet of water. In other words, why does the color of the streambed get warmer than the local color of the stone, and then cooler as it gets deeper?

My hypothesis is that a foot or two of water depth subtracts, through scattering, the cool wavelenths of the light that bounces off the bottom. Therefore, light passing through the water and illuminating the bottom, returns to our eye relatively warmer. It’s also darker because of the light lost to reflection off the surface (which we covered in previous posts: part 1, part 2, and part 3.).

I hesitate to show a Sargent in the same post as my own work, but he captures and accentuates these effects so beautifully. Note the warm stream bottom at the right of the painting below, called "Dolce Far Niente." The cooler colors at left are not from depth effects so much as from the addition of cool sky light off the surface.

Why are the deeper parts cooler, even in the absence of reflection? The second half of my theory is that in deeper water we’re seeing less of the light simply bouncing off the bottom; we’re seeing more of the blue light that has been scattered in all direction—the same reason that infinite depths of air looks bluer.

I don’t know: maybe I’m wrong, or maybe someone can explain it better. Anyway, I love the Sargent above, which shows a stream that's not deep enough for the blue-depth color, but it has the warming effect in the shallows, and a miraculous feeling of the image of the bottom distorted by the rippled surface of the water.
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The Sargents are from the Brooklyn Museum, link.
Previous GurneyJourney posts on transparency of water, link.
and water reflections, part 1, part 2, and part 3.

14 comments:

Erik Bongers said...

Two thinks come to mind.

1. The other day I was walking past a construction site. Water had been pumped up for weeks and the gutter had turned all red due to iron in the water.

2. In Italy or Greece, when an old mosaic has turned bleached and dull, they can bring back some of it's colorful glory by making the floor wet.

So I think minerals and metal in the water may change the color of the river bed.
Also when walking through a dry river bed, it's practically always very gray, but when it starts raining, the stones and pebbles turn red-brown again.

I assume more ideas will popup here, and the reason for the colors in a river bed is a combination of them.

jeff f said...

Is it not the physical properties of water that create what we see.

Water is dense, and heavy even though is not a solid it's density creates the visual that we see in a setting that your describing.

I see that as the stream is getting deeper it reflects more of what is above it. Also as the water is deeper there are more micro organisms which effect the transparency of the water. I think is also part of the what effects what we see.

Also as Erik states the very nature of water, making things wet will change the color and value of the objects. Rocks are made up of minerals and metals so I would imagine this is what we are seeing.

This is an interesting painter Stanley Meltzoff takes painting water to a whole new level, I guess you can call this plein underwater painting...

www.stanleymeltzoff.com

Katherine Tyrrell said...

I've not got a clue about the colour changes but Bravo for trying to paint like Sargent - one of my favourite painters - and for endeavouring to paint like watercolour in oils!

There's an even nicer one water one - in which the colour is spectacular - which I'd tell you about if I could only remember which museum has it. It's the one with the boy who's going swimming and it's from the alpine series.

Sydney Harper said...

Don't know if this helps or not. From my scuba diving days, I remember that warmer colors are absorbed by water. In my "New Science of Skin and Scuba Diving" book (now not so new), it says reds are absorbed in the first few feet, followed by orange at 15 feet, and yellow at 30 feet. I'm guessing this is for clear water. I'm assuming the depths would be less for less transparent water. Information on underwater photography might provide some useful clues.

Decker said...

If you can, wet the stones that you see. I'll bet thy stones look warmer when wet. This probably explains why the underwater stones near the surface look warmer. A thin film of water on a smooth stone achieves the same effect as polishing the stone, making the 'true' color of the minerals visible. If the rocks are largely sandstone, this 'true' color will be warm. When dry, the same stone will appear less colorful and less warm. Not sure why, but I suppose the reason is a combination of dust, dried salts from previous evaporation, and diffuse reflection from the irregular surface of the dry stone, perhaps also some oxidation.

Cooler colors with depth are undoubtedly due to the greater absorption of long wavelengths (reds, oranges,...) in H20. Light that penetrates the water surface, reaches the rocks below and then bounces back to your eye has lost it's long wavelengths. This is what makes ocean water green and blue (short wavelengths).

Dianne Mize said...

I know so little about physics that I dare not guess the answer to your query. But to perceive it and express it transcends the knowledge anyway. Sargent did that and so did you. What interests me is I can hear the water in both.

Erik Bongers said...

Color of water

James Gurney said...

It appears that this is one of those effects where there are a lot of separate contributing factors, and it turns out that everyone who commented gave a different but valid facet of the truth. Thanks to all of you, I'm understanding it much better.

Thanks, too, Erik for that link to the Wiki page on the color of water (I'm becoming quite a fan of Wiki, with 40 times as many entries as my beloved Britannica). That entry did a good job of unraveling all the different factors.

Joe Kazimierczyk said...

I can't answer any of your questions but I just wanted to say I love your painting and whatever causes these color variations in water, you've captured the effect very well!

Izzy Medrano said...

I think this one actually has a simpler answer. Or at least it's how it was broken down in the literature I found.

Basically, the color spectrum runs a gamut of light wavelengths. Short to long, Infrared, to Ultraviolet. And as you go deeper into particulate atmosphere, like a soft haze in a landscape painting, or deep under water, you begin to lose some of your warm colors because they are the brightest, and the most easily reflected.

In a landscape, the warm colors lose intensity the farther you go into the distance, because particles in the air begin to seep away your high chroma. Saturation drops universally, but most strongly in the warm part of the spectrum.

Deep water is the best indicator of this, because you can actually exist in the 'distance' from a "particle perspective". As you swim ever deeper, the color is lost, and all takes on a blueish hue. They have to use special deep water photo-flashes to take pictures. Because these bring back all the wavelengths that are lost as you move down the "chroma-climes". (made up phrase. ^_^)

So, long story short... It comes down to wavelength of light. And particulate atmosphere. Though I think this site might help explain it better:

http://www.wonderquest.com/DeepWaterColors.htm

Izzy Medrano said...

And incidentally, I'm a MASSIVE fan of this site. As a painter, myself, you've made me aware of so much new and amazing stuff! This collection of observations and thoughts is nigh on genius, brother! Love it. I may not comment tons, but I'm here ALL the time.

Just wanted to say thanks!

Artoonator said...

I've been so fascinated by this every time I drew plein air. Please see my most recent plein air water studies at http://digi-sketch.blogspot.com
I try to do it using just color, no details.
Your study rocks!

Israel Yang said...

Hi James,
What are you seeing can likely be explained by Fresnel effect.
http://www.3drender.com/glossary/fresneleffect.htm

Fresnel reflection says a reflective surface is more reflective at a glancing angle.
This picture shows it very well:
http://www.harrishillresort.com/files/images/Shallow%20waters.jpg

You can see into the water that's nearer to the photographer, and see the bottom of it (sand), and near the horizon you do not see into the water at all, all you see is the reflection of the sky.

Most photos and paintings are done with the painter standing at the edge of the water, or where it's shallow, that's why one might think this color becomes bluer as it gets deeper, because the deeper water is usually farther away from the observer and he is looking at its surface at a glancing angle.

It has something to do with water depth as well. If we now move the observer to be floating in the middle of the ocean, and ask him to look near the horizon, the water that's nearest to him would be not very reflective, and he would be able to see into the water much better than he could near the horizon, but he wouldn't be able to see the warm yellow sand beneath him simply because the water is too deep.

James Gurney said...

Thanks, Israel, that's a good explanation.