Weather forecasters and news people have been broadcasting stories about the effects of “El Niño.” These stories talk about rain storms, floods, and snow falls higher than normal in the United States. For instance in California, the snowpack is at 93% and pages of Lake Folsom that had been dry ground for most of the last three drought-stricken years are once again under water. Before discussing El Niño, a review of basic earth physics is good.
The Earth is a big ball clothed in a crust of mostly water and cloaked with a covering of air. The Earth is a heat transfer system. This ball is unevenly heated because its axis tilted compared to the equator of the sun and of the solar system. This uneven heating causes summer and winter. It also causes ocean currents and winds across the globe. Sticking through the water is dry land. The ocean currents flow around the land. Meanwhile, the atmosphere absorbs solar heat, absorbs and stores heat from the land, and blows it around the world via cyclones, anti-cyclones,, hurricanes, tornadoes, breezes, temperature inversions, micro-climates, and other “features.” This brief description is an over-simplification of all that goes into making weather, climate and multi-year events like El Niño.
The oceans provide a mighty hand in the shaping of the Earth’s energy transfer activities. The oceans as a group are 75% of the Earth’s surface, and each ocean affects this system uniquely. There are five oceans on Earth: the Atlantic, Arctic, Indian, Antarctic, and Pacific. The Pacific, and to some extent the Indian Oceans are where El Niño lives. It is centred in the Pacific, but affects weather globally because the Pacific contains 30% of the Earth’s surface area.
Then what is El Niño and how did it get that name? El Niño is Spanish for “The Boy” or the “Male Child” a reference to Jesus Christ. El Niño builds up in winter and early spring, between Christmas and Easter, two holidays that celebrate this “boy” and was discovered by some of the Chilean and Peruvian scientists in the late 1800’s. It results from a rise in ocean temperatures in the equatorial Pacific Ocean, extending toward South America. This often causes increased rainfall in North America, which is why forecasters were predicting an end of a slowing down of the California drought. This year’s California rainfall has been higher than last year’s, with abundant snow in the middle and eastern U.S. and northern Eruope as well.
An opposite effect occurs when the equatorial Pacific Ocean cools. This is La Nina (little girl). La Nina is caused by cool ocean water, and relatively dry weather. Meteorologists call the El Nino/La Nina cycle, the El Nino/Southern Oscillation (ENSO). These cycles last between two and seven years. Recent El Ninos occurred in 1987-8 and 2003-2004. Some are predicting that this will be one of the largest on record.
In any case, El nino is one of the forces of nature that forms the climate found on Earth.