On a mid-January morning in Yellowstone National Park, the only contrast seems to be between the dark water of the river and the shoreline. On closer inspection, the mist coming off the river is condensing and forming frost on the grasses along the shoreline, as shown in this photo. This process seems to happen every morning while I have been here. The frost gives contrast to the river and in other areas it gives contrast against the trees. There is cold air above warm river water, and the grasses provide a point for the frost to form.