CLOSE

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.

Original image
Courtesy Murdoch University
arrow
Animals
Australian Scientists Discover First New Species of Sunfish in 125 Years
Original image
Courtesy Murdoch University

Scientists have pinpointed a whole new species of the largest bony fish in the world, the massive sunfish, as we learned from Smithsonian magazine. It's the first new species of sunfish proposed in more than 125 years.

As the researchers report in the Zoological Journal of the Linnean Society, the genetic differences between the newly named hoodwinker sunfish (Mola tecta) and its other sunfish brethren was confirmed by data on 27 different samples of the species collected over the course of three years. Since sunfish are so massive—the biggest can weigh as much as 5000 pounds—they pose a challenge to preserve and store, even for museums with large research collections. Lead author Marianne Nyegaard of Murdoch University in Australia traveled thousands of miles to find and collected genetic data on sunfish stranded on beaches. At one point, she was asked if she would be bringing her own crane to collect one.

Nyegaard also went back through scientific literature dating back to the 1500s, sorting through descriptions of sea monsters and mermen to see if any of the documentation sounded like observations of the hoodwinker. "We retraced the steps of early naturalists and taxonomists to understand how such a large fish could have evaded discovery all this time," she said in a press statement. "Overall, we felt science had been repeatedly tricked by this cheeky species, which is why we named it the 'hoodwinker.'"

Japanese researchers first detected genetic differences between previously known sunfish and a new, unknown species 10 years ago, and this confirms the existence of a whole different type from species like the Mola mola or Mola ramsayi.

Mola tecta looks a little different from other sunfish, with a more slender body. As it grows, it doesn't develop the protruding snout or bumps that other sunfish exhibit. Similarly to the others, though, it can reach a length of 8 feet or more. 

Based on the stomach contents of some of the specimens studied, the hoodwinker likely feeds on salps, a jellyfish-like creature that it probably chomps on (yes, sunfish have teeth) during deep dives. The species has been found near New Zealand, Australia, South Africa, and southern Chile.

[h/t Smithsonian]

Original image
Gregory H. Revera, Wikimedia Commons // CC BY-SA 3.0
arrow
Space
Study Suggests There's Water Beneath the Moon's Surface
Original image
Gregory H. Revera, Wikimedia Commons // CC BY-SA 3.0

Astronauts may not need to go far to find water outside Earth. As CNN reports, Brown University scientists Ralph E. Milliken and Shuai Li suspect there are significant amounts of water churning within the Moon’s interior.

Their findings, published in the journal Nature Geoscience, lean on the discovery of glass beads encased in the Moon’s volcanic rock deposits. As recently as 100 million years ago, the Earth’s moon was a hotbed of volcanic activity. Evidence of that volatile time can still be found in the ancient ash and volcanic rock that’s scattered across the surface.

Using satellite imagery, the researchers identified tiny water droplets preserved inside glass beads that formed in the volcanic deposits. While water makes up a small fraction of each bead, its presence suggests there’s significantly more of it making up the Moon’s mantle.

Milliken and Li aren't the first scientists to notice water in lunar rocks. In 2008, volcanic materials collected from the Moon during the Apollo missions of 1971 and 1972 were revealed to contain the same water-flecked glass beads that the Brown scientists made the basis of their recent study. They took their research further by analyzing images captured across the face of the Moon and quickly saw the Apollo rocks represented a larger trend. "The distribution of these water-rich deposits is the key thing," Milliken said in a press statement. "They're spread across the surface, which tells us that the water found in the Apollo samples isn't a one-off. Lunar pyroclastics seem to be universally water-rich, which suggests the same may be true of the mantle."

The study challenges what we know about the Moon's formation, which scientists think occurred when a planet-sized object slammed into the Earth 4.5 billion years ago. "The growing evidence for water inside the Moon suggests that water did somehow survive, or that it was brought in shortly after the impact by asteroids or comets before the Moon had completely solidified," Li said. "The exact origin of water in the lunar interior is still a big question."

The findings also hold exciting possibilities for the future of space travel. NASA scientists have already considered turning the Moon into a water station for astronauts on their way to Mars. If water on the celestial body is really as abundant as the evidence may suggest, figuring out how to access that resource will definitely be on NASA's agenda.

[h/t CNN]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios