Today’s Wonder of the Day was inspired by Maryann from AL. Maryann Wonders, “How does el nino affect the weather in the North Eastern part of the US?” Thanks for WONDERing with us, Maryann!
Do you like to keep an eye on the weather? Or do you rely on friends and family members to tell you when to pack a jacket or a raincoat? For those involved in a lot of outdoor activities, keeping an eye on the weather forecast is an important part of planning. After all, you don't want to be stuck outside without the proper clothing and gear.
Often we don't give the weather much thought unless it's making news. If you're in the middle of a long drought or if severe storms are wreaking havoc in your area, the weather may dominate the headlines. People want to know why certain weather events occur. Did you realize that your local weather might be impacted by events thousands of miles away?
In the midst of winter in certain years, there's one weather phenomenon that you might hear about frequently: El Niño. But what exactly is El Niño? And how does it affect weather around the world?
El Niño is a Pacific Ocean climate cycle that's one of the phases of what's known as the El Niño-Southern Oscillation (ENSO) cycle. The ENSO cycle involves temperature fluctuations between the ocean and the atmosphere in the eastern Pacific Ocean near the equator.
During an El Niño episode, warm tropical waters in the western Pacific Ocean shift to the east along the equator toward the South American coast. Instead of the warmest waters staying near Indonesia and the Philippines, these waters sit off the shore of northwestern South America during an El Niño cycle. This is why El Niño is often known as the warm phase of ENSO.
If you know Spanish, you've probably already figured out that El Niño means "the little boy." It's also often interpreted as "Christ child," because Peruvian fishermen who first noticed this weather phenomenon way back in the 1600s called it El Niño de Navidad. Since El Niño tends to be strongest during December and January, the fishermen gave it a name related to the Christmas season.
Occasionally, the opposite phenomenon occurs. When trade winds blow warm water even farther west than normal, this "cold phase" of ENSO is called La Niña or "the little girl" to indicate it has the opposite effect of El Niño.
El Niño and La Niña cycles usually last 9-12 months. They're difficult to predict, because scientists don't fully understand what causes them to occur. El Niño cycles occur more often than La Niña cycles. Scientists estimate that El Niño cycles happen, on average, every 3-5 years, although they can happen as frequently as every two years or as rarely as every seven years.
So why does El Niño make big news when it occurs? Not only does El Niño affect Pacific Ocean processes, but it also has a major impact on global weather and climate. Tropical storms shift eastward, impacting both North and South America.
Strong El Niño cycles usually lead to above-average precipitation and below-average temperatures during the winter in the southern half of North America, while the northern half of the continent experiences below-average precipitation and above-average temperatures. Northwestern South America often sees record rainfalls during El Niño cycles. Fishing in these areas is impacted, too, as fish move north and south to seek colder waters.
The effects of El Niño aren't just limited to North and South America, though. Australia and Southeast Asia see hotter than normal temperatures, and it's not uncommon for these areas to suffer severe droughts. El Niño-induced droughts can also stretch as far as southern Africa and India.