What Is El Niño? What Causes El Niño?

What Is El Niño? What Causes El Niño?
El Niño has an almost legendary reputation among the masses as a disruptive force in our weather patterns. Despite most having little real knowledge of El Niño, or what its effects really entail, it is a fun thing to say and an easy explanation whenever something strange happens with the weather. But just what is El Niño, and what causes it? Let’s try to boil it down to the actual facts.

What Is El Niño?

El Niño is not some magical storm or harbinger of doom, it is merely part of a routine weather pattern that comes around once or twice a decade. Admittedly, it can cause some very unusual patterns and extreme results. It is one component of a recurring climate pattern known as ENSO (El Niño-Southern Oscillation). The other two parts being La Niña, which is essentially the opposite of El Niño, and “neutral,” which is any time period when most climatic factors are relatively average.

El Niño takes place when surface temperatures in the Pacific Ocean rise for an extended period of time. This leads to a change in air temperature in certain areas, ultimately creating a ripple effect that shapes weather patterns around the world. It is usually followed immediately by La Niña, although not always.

What Causes El Niño?

Trade winds are one of the most influential factors in determining climate patterns. And, like all aspects of weather, they vary over time. Normally the trade winds blow east to west across the Pacific Ocean, pushing the cooler water toward Asia. El Niño occurs in a year when the trade winds weaken, or even reverse, meaning less cool water is churned to the surface. The warmer than usual surface water results in warmer air, affecting winds even more and leading to heat being shuffled to different areas.

How Does El Niño Affect Weather Around the World?

In terms of average overall temperature on the planet, El Niño years are warmer than normal. This is in large part because a major symptom is warmer air in the Pacific, which is only one of 5 major oceans but happens to cover over 30 percent of the Earth’s surface. El Niño typically occurs every 2 to 7 years and lasts between 9 and 12 months, although sometimes it can continue for as long as 2 years. It starts in late spring and peaks in strength between November and February, with the main result being more extreme weather events. El Niño affects many different weather zones in roughly the same way each time.

  • South America experiences flooding on the Pacific side and drought on the Atlantic side.
  • The tropical Pacific sees much warmer temperatures.
  • Indonesia, Southeast Asia, and India receive dry air and less rain, often leading to drought.
  • Alaska and the Pacific Northwest will be warmer than usual.
  • Most southern states will be cooler and wetter, and changes in wind direction lead to a far greater risk of tornadoes.
  • It is normally drier in the southeastern states and the Caribbean, which is at least partially beneficial, as El Niño years typically feature a less extreme hurricane season.

Why Is It Called El Niño?

Long before scientists got involved and studied all the causes, effects, and patterns of El Niño, South American fishermen had recognized this unusual phenomenon. They may not have understood the reasons behind it, or known that it was just as disruptive in many other parts of the world, but they certainly noticed the cyclical return of warmer Pacific waters and unusual weather patterns. They named it “El Niño,” which translates literally to “The Little Boy,” but was more importantly the slang term used to describe the baby Jesus Christ. This connection was made because the most extreme effects were usually felt around Christmas, when fish became scarce in the warmer waters and flooding hit the mainland.

The most important thing to remember about El Niño is that it is a naturally occurring, cyclical weather event. The exact details of each El Niño will certainly be altered by climate change along with all other aspects of our weather patterns, but essentially there is nothing that can be done to prevent or affect it. These days, however, scientists can accurately predict their occurrences, allowing people in affected regions an opportunity to prepare in advance.

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