Christopher C. Chapman

The river that circles Antarctica does not flow in a single channel: it sometimes splits into branches, sometimes merges into one stream. That is what the fronts of the Southern Ocean look like on maps built from satellite data on sea surface height. Previously, these fronts were sought along lines of equal water level, and they seemed to creep slowly southward.

An artist painting the ocean does not limit themselves to two colors: warm and cold. Likewise, climatologists studying El Niño increasingly speak of a whole palette of shades. El Niño is a warm current off the coast of Peru that, every few years, alters weather across the planet. Its counterpart, La Niña, brings cold.