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What Is El Niño, and Why Does It Have Such a Big Impact?

Sea surface temperature anomalies, in °C, January 24–31, 2016

A snowstorm in the Midwest this week has its roots in a weather pattern influenced by El Niño—a disturbance that dropped several inches of rain in California, traversed the Rocky Mountains, and spun-up a formidable blizzard that threatens to produce up to a foot of snow across the central United States. El Niño has taken on an almost legendary quality in the United States, entering the collective mind of the public in the late 1990s as an epic weather pattern that drenches California in an unending deluge of tropical moisture.

An El Niño is the abnormal warming of sea surface temperatures in the eastern equatorial Pacific Ocean. The event occurs when winds over the Pacific Ocean near the equator slow down or reverse direction, allowing unusually warm water to accumulate around the eastern part of the equatorial Pacific. When sea surface temperatures in this portion of the Pacific climb 0.5°C above average for seven consecutive months, it’s officially considered an El Niño. Now, an upward shift of one-half of one degree doesn’t sound like much—it’s not!—but, in a similar way to a fever in the human body, it doesn’t take much abnormal heat to make a huge impact both on the ocean and the atmosphere above it.

How can warm water in the Pacific Ocean affect the weather thousands of miles away? Everything is connected. One of the most heavily advertised effects of El Niño is that it can squash the Atlantic hurricane season as the warm water triggers thunderstorms in the eastern Pacific, causing strong upper-level winds to flow east over the Caribbean and Atlantic. This wind shear tears the tops off thunderstorms, keeping tropical activity to a minimum. This is an easily observable effect that we experienced just this past summer. However, the warmer water can also alter the jet stream, which is how we most commonly feel its influence here in the United States.

The jet stream is a fast-moving river of air in the upper levels of the atmosphere that’s usually located between 25,000 and 35,000 feet, the typical cruising altitude for commercial jets. This ribbon of powerful winds is caused by the temperature difference between the tropics and the poles. Weather exists as a result of nature trying to balance itself out—in this case in the Northern Hemisphere, rising warm air in the tropics flows north toward the Arctic, turning east thanks to the Coriolis effect. The resulting river of westerly winds is the jet stream.

The subtropical jet stream over the southern U.S. on February 5, 2016. Source: Tropical Tidbits

During the summer months, the jet stream is usually weaker and stuck in the higher latitudes. This is why weather is generally calmer during the summer, allowing long stretches of hot, humid weather only broken by occasional pop-up thunderstorms. During the cooler months, however, the north-south temperature gradient is much sharper, allowing the jet stream to dive south over the United States (and sometimes even farther south than that). This curvy, dippy jet stream provides us a constant offering of volatile weather, bringing everything from heavy rain or snow to extreme bouts of cold weather.

This is where El Niño factors in. There are actually two jet streams in the Northern Hemisphere: the polar jet stream, which circulates in the higher latitudes, and the subtropical jet stream, which we’ll often find around the southern United States. The polar jet is what brings us our deep shots of frigid air during the dead of winter, and the subtropical jet is often at least partially responsible for the huge, historic snowstorms that occasionally whomp the East Coast.

When the water in the eastern equatorial Pacific Ocean is abnormally warm like it is during an El Niño, it can affect air temperature above the surface. The warmer air allows the subtropical jet stream to grow stronger and establish itself over the southern United States, shoving the polar jet stream farther north near the border between the U.S. and Canada. This brings stormy weather to the southern half of the United States, often manifesting itself in wet low-pressure systems that smack California before slowly trundling across the rest of the country. This also tends to keep the northern United States drier and warmer than normal, though snowy conditions and arctic blasts aren’t uncommon.

If you hear people talk about El Niño causing flooding and snow out west or news anchors report that “El Niño brought heavy rain to Los Angeles yet again today,” take comfort in the fact that you now know that’s not true. El Niño doesn’t directly cause rain or snow or heat or cold in the United States, and El Niño doesn’t make landfall like a hurricane, either, since it’s just abnormally warm ocean water. If all of that warm water ever comes ashore, we’ll probably have a few more problems than worrying about scientific accuracy and semantics. El Niño isn’t and won’t always be the cause of our weather woes this season, but it sure doesn’t help.

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Space
More Details Emerge About 'Oumuamua, Earth's First-Recorded Interstellar Visitor
 NASA/JPL-Caltech
NASA/JPL-Caltech

In October, scientists using the University of Hawaii's Pan-STARRS 1 telescope sighted something extraordinary: Earth's first confirmed interstellar visitor. Originally called A/2017 U1, the once-mysterious object has a new name—'Oumuamua, according to Scientific American—and researchers continue to learn more about its physical properties. Now, a team from the University of Hawaii's Institute of Astronomy has published a detailed report of what they know so far in Nature.

Fittingly, "'Oumuamua" is Hawaiian for "a messenger from afar arriving first." 'Oumuamua's astronomical designation is 1I/2017 U1. The "I" in 1I/2017 stands for "interstellar." Until now, objects similar to 'Oumuamua were always given "C" and "A" names, which stand for either comet or asteroid. New observations have researchers concluding that 'Oumuamua is unusual for more than its far-flung origins.

It's a cigar-shaped object 10 times longer than it is wide, stretching to a half-mile long. It's also reddish in color, and is similar in some ways to some asteroids in own solar system, the BBC reports. But it's much faster, zipping through our system, and has a totally different orbit from any of those objects.

After initial indecision about whether the object was a comet or an asteroid, the researchers now believe it's an asteroid. Long ago, it might have hurtled from an unknown star system into our own.

'Oumuamua may provide astronomers with new insights into how stars and planets form. The 750,000 asteroids we know of are leftovers from the formation of our solar system, trapped by the Sun's gravity. But what if, billions of years ago, other objects escaped? 'Oumuamua shows us that it's possible; perhaps there are bits and pieces from the early years of our solar system currently visiting other stars.

The researchers say it's surprising that 'Oumuamua is an asteroid instead of a comet, given that in the Oort Cloud—an icy bubble of debris thought to surround our solar system—comets are predicted to outnumber asteroids 200 to 1 and perhaps even as high as 10,000 to 1. If our own solar system is any indication, it's more likely that a comet would take off before an asteroid would.

So where did 'Oumuamua come from? That's still unknown. It's possible it could've been bumped into our realm by a close encounter with a planet—either a smaller, nearby one, or a larger, farther one. If that's the case, the planet remains to be discovered. They believe it's more likely that 'Oumuamua was ejected from a young stellar system, location unknown. And yet, they write, "the possibility that 'Oumuamua has been orbiting the galaxy for billions of years cannot be ruled out."

As for where it's headed, The Atlantic's Marina Koren notes, "It will pass the orbit of Jupiter next May, then Neptune in 2022, and Pluto in 2024. By 2025, it will coast beyond the outer edge of the Kuiper Belt, a field of icy and rocky objects."

Last week, University of Wisconsin–Madison astronomer Ralf Kotulla and scientists from UCLA and the National Optical Astronomy Observatory (NOAO) used the WIYN Telescope on Kitt Peak, Arizona, to take some of the first pictures of 'Oumuamua. You can check them out below.

Images of an interloper from beyond the solar system — an asteroid or a comet — were captured on Oct. 27 by the 3.5-meter WIYN Telescope on Kitt Peak, Ariz.
Images of 'Oumuamua—an asteroid or a comet—were captured on October 27.
WIYN OBSERVATORY/RALF KOTULLA

U1 spotted whizzing through the Solar System in images taken with the WIYN telescope. The faint streaks are background stars. The green circles highlight the position of U1 in each image. In these images U1 is about 10 million times fainter than the faint
The green circles highlight the position of U1 in each image against faint streaks of background stars. In these images, U1 is about 10 million times fainter than the faintest visible stars.
R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF

Color image of U1, compiled from observations taken through filters centered at 4750A, 6250A, and 7500A.
Color image of U1.
R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF

Editor's note: This story has been updated.

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Scientists Analyze the Moods of 90,000 Songs Based on Music and Lyrics
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Based on the first few seconds of a song, the part before the vocalist starts singing, you can judge whether the lyrics are more likely to detail a night of partying or a devastating breakup. The fact that musical structures can evoke certain emotions just as strongly as words can isn't a secret. But scientists now have a better idea of which language gets paired with which chords, according to their paper published in Royal Society Open Science.

For their study, researchers from Indiana University downloaded 90,000 songs from Ultimate Guitar, a site that allows users to upload the lyrics and chords from popular songs for musicians to reference. Next, they pulled data from labMT, which crowd-sources the emotional valence (positive and negative connotations) of words. They referred to the music recognition site Gracenote to determine where and when each song was produced.

Their new method for analyzing the relationship between music and lyrics confirmed long-held knowledge: that minor chords are associated with sad feelings and major chords with happy ones. Words with a negative valence, like "pain," "die," and "lost," are all more likely to fall on the minor side of the spectrum.

But outside of major chords, the researchers found that high-valence words tend to show up in a surprising place: seventh chords. These chords contain four notes at a time and can be played in both the major and minor keys. The lyrics associated with these chords are positive all around, but their mood varies slightly depending on the type of seventh. Dominant seventh chords, for example, are often paired with terms of endearment, like "baby", or "sweet." With minor seventh chords, the words "life" and "god" are overrepresented.

Using their data, the researchers also looked at how lyric and chord valence differs between genres, regions, and eras. Sixties rock ranks highest in terms of positivity while punk and metal occupy the bottom slots. As for geography, Scandinavia (think Norwegian death metal) produces the dreariest music while songs from Asia (like K-Pop) are the happiest. So if you're looking for a song to boost your mood, we suggest digging up some Asian rock music from the 1960s, and make sure it's heavy on the seventh chords.

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