Merchant's Row 8"x8" oil on canvas panel
John Carlson made many useful observations in his book, Carlson's Guide to Landscape Painting. One of the most fundamental is that light from the sky illuminates planes in the landscape differently depending on their angle to the sun. This concept of value planes in the landscape is known as Carlson's Theory of Angles. He proposes that we simplify down to four planes in the landscape: 1) the ground plane, 2) the verticals, such as trees, 3) the plane of mountains or slanted roofs, 4) and finally, the sky.
When the sun is overhead, the sky will be the lightest value. The ground plane, which gets the full force of the sun, will be the second lightest. The plane of the mountains and slanted roofs, will be third lightest, and the darkest will be the trees. I hope that you can see this in the image below, which represents the upper left corner of the painting above. The islands fall in plane 3, like mountains and slanted roofs.
There are, of course, complications to this, when the sun is not directly overhead. When the sun is low in the sky, shadows are cast on the ground plane, and verticals can be in sunlight or shade. Where the ground plane is water things can be different. In my example here, the water is relatively calm, and follows Carson's rule. But the surface of the water in wind will be darker than when the sea is calm and reflecting the sky like a mirror. Even with those caveats, when I keep Carlson's theory in mind, I'm able to find these values in my landscape and use them to make a stronger painting.
Bobbi - Painter. Sketcher. Teacher. Boat and Dog Lover.