mination? Absolutely. Brilliant, balanced natural light occurs under a high sun and a clear sky. All hues are rendered perfectly, and both the colorfulness contrasts and lightness contrasts are optimal. All directly illuminated surface colors appear in their unbiased local color and can be painted in that way.
In daylight shadows are tinted with a desaturated red blue (such as indanthrone blue, PB60 or a grayed cobalt blue, PB28), not a purple. A general yellowing of color or a slightly increased saturation from orange to yellow green and a decreased saturation from magenta through cyan can be used for expressive emphasis or to show variations in illuminance intensity produced by the angle of surfaces to the light source ("brighter" illuminance = yellower or, for warm hues, more saturated color).
Dim light either means greatly reduced illuminance or filtered (chromatically altered) light. If the light is dim, the chromatic balance among colors, measured in the spectral composition of the reflected light, is roughly the same. However, it produces very different mood effects than bright light of the same chromaticity. Dim light seems softer, more intimate and pleasant if it has a "warm" chromaticity, but seems cold, gloomy and depressing if it has a "cool" chromaticity. In either case the average value may be darker, but values always contract toward the average value (extreme lights and darks disappear, with the larger shift toward gray occurring in the dark values).
If the light is filtered, the color depends on the tinting layer that produces the filtering. Overcast clouds produce a darkening that is approximately the same chromaticity as unfiltered daylight, or slightly bluer. In painting this is commonly represented as a shift toward blue, with a loss of colorfulness (graying) and contrast in all colors, but especially warm colors (which shift toward green).
Near sunset, short or "blue" wavelengths are strongly filtered from sunlight by atmospheric dust and smoke, causing the "blue" component in all colors to darken and the "red" component to appear unnaturally bright. This causes greens to shift toward yellow and the dull yellow or red of tree bark and wood to appear unnaturally red.
Night light is is viewed under scotopic vision, which means colors are principally symbolic rather than imitative. Even so, the typical representation of night relies on a near monochrome palette of blues or blue greens, with yellow accents contributed by isolated artificial lights and the near surfaces they illuminate.
How do I make a color warmer or cooler? The answer depends on whether your axis of reference is the illumination or the hue circle. If you want to make a color warmer within a certain kind of illumination (that is, the light in any representational landscape or portrait), then the "warmest" color is typically shifted from red orange toward the color of the illumination. Greenish light makes oranges and yellow warmest, because reds are dulled almost to blacks; orange light makes oranges warmest, and dulls magentas and yellow greens.
If the axis of reference is in terms of the hue circle (as would be used in nonrepresentational color design, for example), then "warmest" color depends on all the colors in the image. However, given the way our visual system is structured and the range of available pigments, a red orange located at a CIELAB hue angle of about 40 or darkened, whitened or dull paints of similar hue, such as burnt sienna, burnt umber, convenience "naples yellow" paints, or quinacridone orange are good standards of comparison.
When you "cool" a warm color in paint mixtures, it is important to use a blue that contains no red reflectance and no green hue. In paints, only indanthrone blue (PB60), phthao blue (PB15 or iron blue (PB27) meet these two criteria. All paints compounded with ultramarine blue or cobalt blue contain some "red" reflectance and give the mixture a purple tint. At the same time, paradoxical shifts can result if you use a saturated "blue" red that contains some "violet" reflectance. This paints wi