As a teenager, I climbed Mount Kilimanjaro. The final ascent began around midnight, and we climbed through the dark, through sunrise, and into the early morning. I remember pausing at one point, just as the sun was rising, and looking out at the clouds thousands of meters below. From that height, they looked like an ocean, rippled with lavender waves. Timelapse films like this one, by filmmaker Martin Heck, remind me of that morning and the sense that I had of the sky as an ocean, flowing, crashing, and surging in ways we cannot appreciate until we slow down and look closer. (Image and video credit: M. Heck/Timestorm Films)