According to Mr. Anderson:
“Wilson developed a rigorous method for painting skies in his large scale dioramas that had its roots in his plein air paintings. While painting outdoors, he would carefully blend progressive tints of his three main colors, the horizon, mid-sky, and upper sky, into a graduated, light-filled sky color.In Wilson’s own words:
“In a typical diorama, Wilson carefully planned the sky colors and usually painted with thirteen bands of color. These colors were pre-mixed to the determined quantity so there would be no color matching midway through the painting of the sky.”
“A typical fair-weather sky, especially at high altitudes, graduates smoothly and evenly from a deep blue (cobalt or ultramarine) overhead, to a clear and much lighter blue, usually a turquoise hue, at perhaps one quarter of the distance from the horizon to the zenith. Below this level the tone usually lightens still more, but the blue color is modified by ground haze.Libyan desert diorama (top) is in the American Museum of Natural History in New York.
"The hue may be somewhat greenish, in very clear weather, or purplish, on hazy days, especially at low altitude. These three tones—upper part of the sky, clear turquoise band and horizon color—may be considered as the key colors for the entire sky. If they are carefully prepared, all the intermediate tones may be obtained automatically by mixing these. This will insure a smooth, even gradation. The process of repeated subdivision naturally results in 13 bands, as the following diagram will indicate."
Read the new chapter of Michael Anderson's biography of James Perry Wilson