The colour of snow - well, that depends.
Photograph I took of the Bow River in Calgary. What colour is snow? We know from experience that it is white. And yet, the above photo would seem to indicate that it may sometimes be blue. On the same day. In the same photo. In fact, snow can be both blue or white and be right beside each other. And if all that wasn't enough, the shade of blue can also differ depending on the situation. So, what sort of devilry is going on here? You may already know the answer to that, and it isn't some tweak of Photoshop that has created it. This is Nature herself and the wonderful world of white balance. Snow reflects all the wavelengths of visible light. The light falling upon the snow is called incident light, and it is the spectral makeup of that light causing the would-be colour change. On a cloudy, gray day, you may find that the snow is pretty much the same colour. Yet, on this day in April of 2017, there was an open blue sky. Dir...