An astronaut snapped this image of wave clouds formed around the Crozet Islands, which lie between South Africa and Antarctica. Clouds like these form when warm, moist air gets pushed up and over a mountain. As it rises, the air cools and its pressure decreases, causing condensation. Pushed out of equilibrium, gravity then pulls the air back downward in the wake of the mountain. That warms the air, causing evaporation. Like a mass bouncing on a spring, the air continues to yo-yo up and down, forming cloudy stripes and clear ones until the energy from its mountain climb is spent. (Image credit: NASA; via NASA Earth Observatory)
Wave Clouds From Space
