Snow scenes can be tricky to gauge in terms of value and contrast, because of the large amount of white present throughout the scene. It is always a good idea to look for a balance of values when selecting a winter scene to paint, otherwise the picture can look washed out and it may then lack impact and depth. Try to include some sunlight to provide cast shadows, as these will bring in the dark element of the value scale and will contrast nicely with any white paper left behind for the snow. Often, shadows are misinterpreted as being lighter than they are and in the video demonstration (see a shorter version of this video below) of this painting on my website, I show how easily this illusion is missed. They are generally brighter in colour due to the amount of reflected light, but even on a bright, snow-covered surface they are still of a dark value. The snow will reflect other colours too, such as grey, blue, yellow, and so on, but these are often so pale the snow will appear consistently white. Use a piece of white paper such as typing paper or even an envelope and place it against your reference to make a comparison. If the snow is off white it will show up against the paper.