I spent part of the winter of 2016 in the Serre Chevalier region of the French Alps. During an afternoon hike on a day of tempestuous weather, I rounded a bend on the side of a peak and the clouds seemed to suddenly drop into the valley below. As the blue sky appeared, the forest began to reveal itself through the cloud and the distant peaks flashed in the sunlight. Moments later the cloud had rolled across and the scene was gone.