Madden-Julian Oscillation

A "wave" of disturbed tropical weather that spreads eastward around the globe on a 30-to-60-day cycle, usually beginning in the Indian Ocean. The disturbance brings periods of enhanced tropical rainfall followed by periods of suppressed rainfall, and it also influences cloudiness and sea surface temperature. Although the Madden-Julian Oscillation originates in the tropics, it influences weather in the subtropics and mid-latitudes as well.