A flow of abnormally warm water across the eastern pacific ocean towards the coast of Peru. It is associated with changing pressure patterns and a reversal of airflow in the equatorial Pacific, a phenomenon referred to as the southern oscillation. An El Niño event is preceded by a strong east to west airflow which pushes warm surface water to the western pacific basin, allowing cold water to well up and take its place in the east. When the southern oscillation brings about a reversal of the airflow, the warm water ponded up in the western pacific flows east again to replace the cold and create an El Niño. The name originally referred to a warm current that appeared off the coast of Peru close to Christmas -hence El Niño, the (Christ) child. Although originally considered a regional event, when strongly developed, El Niño can keep areas in the eastern pacific warmer than normal for periods of a year or more, and it is now recognized as being of global significance, capable of disturbing weather patterns in many parts of the world.