If you've done any reading about winter painting, you'll have heard over and over again that snow is rarely white. This is true. I've seen the full spectrum in the snow, both in shadow and sunlit areas. Warm pinks, golden yellows, cornflower blue -- even subtle greens. Yes, green!But what's most interesting about snow isn't the color but the value. If you measure value on a scale of 1 to 10, with 1 being black and 10 white, I don't think I've ever seen snow darker than a 6 or 5. This is perhaps most obvious on an overcast day when the snow has an almost overall bright value, even in the deep woods. But I've found this to be true even on a crisp, clear day when the sky is scraped clean of clouds and is such a deep blue you'd swear you were looking into the depths of the Mediterranean Sea. Again, even in the shadows of the deep woods, the snow is quite light.
Surprisingly, snow in shadow is often very close to the value of the sunlit snow. This is due to so much light bouncing off the surrounding snow and into the shadows. It's like being inside a hall of mirrors with a single beam of light shining in -- there's no escape from the light.
Whenever I paint snow in shadow, I first paint it fairly dark, exaggerating the darkness a step in value. I may paint it as a 4. This helps me pay attention to the patterns of snow. They are dark and crisp so I can get the patterns just right. But later, after I've "worked up" the other areas of the painting, this value needs to be adjusted. I go back into the shadowed snow with lighter paint...then even lighter paint...and finally, lighter yet. I try "push" the value of the snow as high as I can, but keep it dark enough so it looks like snow in shadow. Sometimes I go too far, and the shadow merges with the sunlit snow. This is how I make those beautifully soft edges, which you'll often see at the ends of the shadow farthest from the object casting it. If this softness isn't in the right spot, though, I'll go back in with a little darker paint to reinforce the shadow concept.
"Barn Shadow" (above; 5x7, oil, plein air) has a striking and dominant shadow in the composition. When I painted it, the day was very clear with intense light on the snow. This was the very darkest shadow I could find.
By the way, this and other paintings in my series of 5x7 plein air snow scenes can be seen here.
