Blue Shadows: What Lights the Shade
On snow, the shadowed side is never grey. It is lit by the sky, and the sky is blue.
Walk out onto old snow around four in the afternoon and the ground has two colours in it. The side facing the sun is warm, almost cream. The side turned away is blue, and not a faint blue either. Nothing has been filtered. Sunlight lands on one slope; the other gets only the second-hand light of the whole dome of sky above it, and that light has always been blue.
Cameras argue with this. Auto white balance reads the cast as an error and pulls it back until the snow is neutral and the shadows go grey and slightly dirty. Leaving the frame a little cool is closer to what the eye actually accepted while standing there. The effect deepens with altitude and with cold, and it peaks in the last hour, when the lit snow turns gold and the shadow behind every ridge sinks further into blue.
As a wallpaper this pairing does quiet work. Warm and cool sit at opposite ends of a scale, so depth arrives without heavy contrast, and the blue side stays calm enough to hold a column of icons without anything getting lost. Most screens spend all day showing rooms with one light in them. A picture with two is a small relief.
