This toy submarine is not bent.

You don’t have to know the scientific formula, but you surely have to understand it to convincingly paint water. 

In this new series of articles, San Diego artist and instructor Ron Lemen will explore the science behind what we see, in order to make our paintings more convincing. In each segment, you’ll learn something new about the natural world. 

Lemen says he believes direct observation is the key, but understanding the physics behind things only improves one’s ability to depict them. “If you care about the subtext, it will show up in your painting,” says Lemen. “You don’t want to get lost in the science of it. You can still feel everything that you feel. But you will move your hand a little more intelligently if you know the science. You’ll know what it is that you are manipulating, and why. It’s the artist who makes the art.”

Snell’s Law deals with the refractive quality of water. It states that the way an object appears as it crosses the border between two media is distorted in a predictable and consistent fashion. As a formula, it is written like this:

Snell’s Law, named after Willebrord Snellius, says that light is refracted in a predictable way based on the speed of light through two media, or by examining their refractive indexes. 

That formula discusses how the angle in which an object hits a plane seems different when viewed through another substance. The example most people are familiar with is a straw in water. The straw seems to bend where it goes from air to the water surface and below. This is because light travels differently through water than it does through air. This is predictable if one knows either the refractive index of each medium or the speed of light through each medium. What it means to you as an artist is that you have to distort lines in order to make a partially submerged object read correctly, and the value and or hue of the object looks different through water as well.

A photo of a mooring rope, by Sfx — Silver Fox.

Here’s a drawing of the rope showing no distortion as it enters the water.

Another error is to mistake the reflection for the refraction.

Be mindful not to paint the rope with as much intensity (chroma) in the water as out of the water. The reflections should have a muted intensity as well.

The goal is to strike the right balance in color, transparency, opacity, angle, and logic of surface displacement. 

Consider this photo by Sfx — Silver Fox. It’s a good example of Snell’s Law, which you will only see when you are close to shore or near something that is passing through the water, such as the mooring line shown here. The obvious mistake that could be made here in trying to paint this into a picture would be to straighten out said object passing through the water or to bend the object in the wrong direction.

Artists sometimes paint the reflection of the rope rather than its refracted appearance in the water, and distort the reflection. Another error artists make is to paint the rope or other object with the same chroma above the water as in the water, or painting the broken reflection of the rope with the same intensity.

Type “photography and Snell’s Law” into your search engine and you will find photography contests that have this effect as one of their contest categories. Educate your eye of the angle of refraction and the next time you go out and paint you won’t be second-guessing your eyes when you see those things passing through the water and skewing heavily.


1 COMMENT

  1. Amazing Jason! You are so professional and have worked so long and hard to get where you are today. I am so proud of you and would love to take lessons from you sometime on how to paint plein air. This has been something I’ve always admired as an artist and I’ve watched you progress to the point you are at today. Fantastis work! Congratulations and Happy New 2012!

  2. Just amazing – look how Jason took a bland scene and brought it ‘alive’ – a place you would want to visit; to explore the middle grounds.

  3. Just amazing – look how Jason took a bland scene and brought it ‘alive’ – a place you would want to visit; to explore the middle grounds.

  4. Just amazing – look how Jason took a bland scene and brought it ‘alive’ – a place you would want to visit; to explore the middle grounds.

  5. Just amazing – look how Jason took a bland scene and brought it ‘alive’ – a place you would want to visit; to explore the middle grounds.

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