Snowdrifts form on the leeside of ridges and vegetation. Wind velocities determine how much snow is moved across and over a landscape. Anytime the wind’s velocity is reduced, the larger snow crystals fall out of the wind stream and deposit into drifts. This drift was about 12 feet high in the Hayden Valley. I stood below the sharp 90 degree edge of the cornice and looked straight up and watched the crystals whirl and spin, and drop below the drift’s edge. During the high speed gusts, shovel’s full of hard icy crystals sifted down on me in the wind eddies so thickly that it was hard to breathe. It was like facing up into a shower head during a cold shower.