Devilishly difficult in the details

Color theory is a great place to get caught up in what you know versus what you see.
Schoodic fog-bow.
It was a splendid North Atlantic morning, looking more like November than August. The horizon was obscured in sea smoke. The rocks at Schoodic Point were covered with gulls who either felt a weather event in the offing or were sick of work. There was an onshore breeze and thunderheads building over Cadillac Mountain.
Plein air painting requires, above all, flexibility. I’d had a different plan for Wednesday, but everyone should spend one day painting the sheer magnificence of Schoodic Point, and today’s weather forecast is iffy. I swapped my plans as well as our location. Instead of teaching about believable greens, I concentrated on the color of light.
Visitors to Schoodic inevitably stop and stare. It’s stupefaction in the face of overwhelming power. 
On a day with a sea fog, all color theory goes out the window. What is the color of light when you are enveloped in a blanket of thick, peaceful, fluffy wool? It’s grey, sometimes tempered with pink, sometimes with blue, but ever-changeable. There’s a lot to leave to the imagination in such a setting. I sometimes paint the fog pale violet, because I like that color, but I don’t want it to become a gimmick.
There are three components to color: hue, saturation and value. They’re all the artist has to lead his viewer through his story, develop points of emphasis, and drive the eye.
I demo through the lunch hour at my workshops…
Value – How light or dark is the paint?
Hue – Where does the color sit on the color wheel? All colors fall into one of the following hue families: red, orange, yellow, green, blue and violet. Within those families, however, are many subdivisions.
Chroma – How much intensity, or “punch” does the color have? A red geranium flower is high-chroma, a fog bank is low-chroma.
That sounds so sensible and neat on paper, but it gets messy on the canvas. The same is true of the color of light.
When the whole visible light spectrum strikes your eye at the same time, you perceive white. In the real world, this doesn’t happen. What you see is always filtered by our atmosphere.
Which is why I was so angry at the gull who thumped me in the shoulder and stole my sandwich from my lips. Rude.
It’s easy to see the gold and peach light of sunset, or the cold light of midday, but what is the color of fog? It’s often a cool, desaturated blue-grey, but that isn’t always true. It depends on the direction you’re looking and the time of day.
Color theory is a great place to get caught up in what you know versus what you see. When that happens, try to understand why it’s not working the way you thought it would. Then paint what you see, or, better yet, paint what you feel.