What happens during El Niño and La Niña events?

Figure1-4

Figure 1-4   During El Niño (left), the trade winds decrease, ocean water piles up off South America, the sea surface temperature increases in the eastern Pacific, and there is a shift in the prevailing rain pattern from the western Pacific to the western Central Pacific. During La Niña (right), the trade winds increase, ocean water piles up in the western Pacific, the sea surface temperature decreases in the eastern Pacific, and the prevailing rain pattern also shifts farther west than normal. (Courtesy of NOAA National Weather Service.)