El Nino, also called the "El Nino-Southern Oscillation" or ENSO, is a change in the ocean-atmosphere system in the eastern Pacific that occurs about every five to seven years. It contributes to significant weather changes around the world, according to the National Oceanic and Atmospheric Administration. Among these changes are increased rainfall across the southern region of the U.S. and in Peru and drought in the West Pacific, affecting Australia and its neighboring nations. During El Nino, the winds at the equator blow from west to east in the Pacific. These winds travel along the surface of the ocean and bring warm surface water heated by the tropical sun to the western coasts of North and South America. Rainfall follows the warm water eastward, with associated flooding in Peru and drought in Indonesia and Australia. A key indicator of El Nino is usually warm temperature along and on both sides of the equator in the central and eastern Pacific. The warming typically starts in the north during late spring or summer and builds to a peak at the end of the year. The events are usually over by the following summer. The changes in ocean temperatures affect the atmosphere. The hot, humid air over the oceans fuels tropical thunderstorms. The hotter the air, the stronger the thunderstorms. As the warmest water spreads, the biggest thunderstorms follow, or move, with it. These thunderstorms pump warm air and humidity more than 50,000 feet into the air. El Nino has had an impact on many nations around the world. Some places got hit with heavy rains and floods, others faced drought, poor crops and starvation. Many different species of fish migrated and coral reefs got damaged. Santiago, Chile has suffered from severe flooding from heavy rainfall and snow. Drought conditions were felt in northeast Brazil, southeastern Africa, and the west Pacific. Pakistan and northwest India were dry, and the normal monso...
