After abnormally rainy days, the sun slid out today, and the sky was blue.
Here's the edge of Goose Lake along the bike trail to UAA.
The sun made the birch trunks white, white.
"RYB (red, yellow, and blue) is a historical set of subtractive primary colors. It is primarily used in art and art education, particularly painting. It predates modern scientific color theory.
RYB make up the primary colors in a painter's color wheel; the secondary colors VOG (violet, orange, and green) make up another triad. Triads are formed by 3 equidistant colors on a particular color wheel; neither RYB nor VOG is equidistant on a perceptually uniform color wheel, but rather have been defined to be equidistant in the RYB wheel.
Painters have long used more than three "primary" colors in their palettes—and at one point considered red, yellow, blue, and green to be the four primaries. Red, yellow, blue, and green are still widely considered the four psychological primary colors, though red, yellow, and blue are sometimes listed as the three psychological primaries, with black and white occasionally added as a fourth and fifth.
During the 18th century, as theorists became aware of Isaac Newton’s scientific experiments with light and prisms, red, yellow, and blue became the canonical primary colors—supposedly the fundamental sensory qualities that are blended in the perception of all physical colors and equally in the physical mixture of pigments or dyes. This theory became dogma, despite abundant evidence that red, yellow, and blue primaries cannot mix all other colors, and has survived in color theory to the present day.
Using red, yellow, and blue as primaries yields a relatively small gamut, in which, among other problems, colorful greens, cyans, and magentas are impossible to mix, because red, yellow, and blue are not well-spaced around a perceptually uniform color wheel. For this reason, modern three- or four-color printing processes, as well as color photography, use cyan, yellow, and magenta as primaries instead. Most painters include colors in their palettes which cannot be mixed from yellow, red, and blue paints, and thus do not fit within the RYB color model. Some who do use a three-color palette opt for the more evenly spaced cyan, yellow, and magenta used by printers, and others paint with 6 or more colors to widen their gamuts. The cyan, magenta, and yellow used in printing are sometimes known as "process blue," "process red," and "process yellow."
To really get into this from a camera perspective, check out Mark Meyers' Photo Journal post "Calculating Color Space Volumes."