A name given to the occasional development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Humboldt current which normally operates. El Nino is an extension of the Equatorial current and leads to an increase in surface water temperature of ten degrees and a decrease in plankton, which thrive in the colder current As a result of this reduction in their food supply the fish population is seriously depleted. It recurs every seven to fourteen years and results from a weakening of the SE Trades in the Pacific.

This is the difference between the incoming and outgoing energy.