What are El Niño and La Niña? El Nino and La Nina are unusual weather phenomena that form over a 10-month period. Both El Nino and La Nina impact climates around the world, each being different depending on the country and region. Normal weather conditions occur when atmospheric pressure is low over northern Australia and Indonesia, and when atmospheric pressure is high over the Pacific Ocean. Winds move from east to west over the Pacific. East-east trade wind flows carry warm surface waters westward and bring torrential rains to Indonesia and northern Australia. Toward the coasts of Ecuador and Peru, warm surface waters are drawn westward and cold water below rises to replace them. This is called upwelling. An El Nino phenomenon occurs every 3 to 7 years. The formation of this is linked to the Pacific Southern Oscillation which is also the circulation cycle of the Pacific Ocean. The Pacific Southern Oscillation (the change in atmospheric pressures) occurs when the easterly trade winds collapse, weaken, or even reverse. By doing so, the rising water stops. The slight weakening of winds causes a slight change in sea surface temperatures, and wind and pressure changes increase. Warm waters from the western Pacific Ocean flow eastward, and sea surface temperatures rise on the west coast of South America. When this happens, wet weather conditions (originally in the western Pacific) move east and dry conditions (normally east) appear in the west. During El Niño events in the Pacific Northwest, the amount of precipitation decreases significantly, winter temperatures become milder, and precipitation is below average. Some economic and environmental impacts include increasing erosion due to strong storm surges, fears that properties built in low-lying areas or on top of unstable cliffs will potentially be flooded or threatened by landslides due to regional climate changes , and various potentially endangered salmon species. . In California, during El Nino, precipitation and snowfall are extreme. Economic and environmental impacts include heavy rainfall, damage from debris flows or mudslides, and rain-induced flooding. Peru's El Nino seasons bring so much precipitation that there is now a lake made of rain, compared to the desert it once was. Several economic and environmental impacts of El Nino include massive flooding or landslides, and because Peru lives in a cold water area, it carries many fish that are caught and sold commercially, but during El Nino, a layer of warm water covers the nutrients. rich waters of the east coast, abruptly stopping upwelling and nutrients failing to rise.