Marcelo Barreiro

Over the warm waters of the Indian and Pacific Oceans, a giant wave of moist air is born every month or two. It creeps eastward at a pedestrian pace, about five meters per second, dragging bands of downpours and droughts behind it. Meteorologists call it the Madden–Julian Oscillation MJO.

An invisible relay race runs through Earth's tropics: a wave of heavy rain and winds, which meteorologists call the Madden–Julian Oscillation, travels eastward at about five meters per second. Most runners tire quickly, but rare marathoners carry the torch all the way across the Pacific.