I have been trying for this sort of shot for at least ten years. Never could get either the free time or the right conditions. We rarely get mist or fog here as the humidity is too low, when we do it tends to be very transient. This last weekend things worked out as the temperature dropped so the snow was actually warmer than the air above leading to a condensation layer just above the ground. The conditions only lasted till just after sunrise, but fortunately were present on both Saturday and Sunday mornings so I was able to get all three planned shots done in one weekend