These broad undulations, viewed in from instruments on NASA’s Aqua satellite, extended over the remote Southern Ocean like waves in the wake of a flotilla. But these were not waves on the ocean. They formed above it, in marine Stratocumulus clouds. And no moving ships produced the wakes.

They formed as the wind flowed over the volcanic peaks of the South Sandwich Islands. Blowing from left to right over the seven peaks, a steady westerly wind developed rising and dipping undulations revealed by the appearance of the clouds. The flotilla of desolate isles, though quite immovable below this flowing ocean of air, seemed on its own mysterious voyage.