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12 Whirling Facts About Tornadoes

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Often spinning at speeds over 100 miles per hour (and in extreme cases over 300 miles per hour), a tornado is a violently rotating column of air in contact with the Earth and the clouds that can cause considerable destruction. The very large and very powerful Tuscaloosa-Birmingham tornado of 2011 lofted a 36-ton empty coal hopper rail car almost 400 feet. The equally impressive Hackleburg tornado of the same day carried jeans from a damaged denim factory more than 40 miles. Here are 12 facts about these dangerous whirlwinds.

1. THE BASIC INGREDIENTS OF A TORNADO ARE WIND SHEAR, INSTABILITY, HEAT, MOISTURE, AND A FORCING MECHANISM.

When winds higher in the atmosphere are moving faster than wind closer to the ground, this creates vertical wind shear, which is a change in wind speed or wind direction with height. Much like a paddle wheel, this wind shear generates horizontal rotation. But to become a tornado, this horizontal rotation needs to become vertical. When a cool, dry air mass covers warm moist air, the overlap creates instability. The hot air wants to rise because it’s less dense, forming updrafts. This updraft can tilt the horizontal rotation into vertical rotation—the beginnings of a tornado.

A cap of warmer air can prevent this rotation from tilting, because it can block the updrafts from penetrating very high into the atmosphere. But if conditions change—say, as the heat of the day reaches its peak by mid- to late-afternoon—rising air from the surface layer of air becomes warmer than the cap, breaking it. Air can now ascend several miles into the sky. A thunderstorm with a rotating updraft—a supercell—has now developed.

However, even when all these ingredients are present, the supercell may not produce a tornado. Scientists are still trying to understand exactly what the triggering mechanism is that turns a supercell into a twister. “The atmosphere has a way of getting the four together in ways with minor differences to either create a large EF5 tornado or a just some rain. We don’t know when and where these ingredients form in just the right way,” Roger Edwards, lead forecaster at the Storm Prediction Center, told Science of the South. Indeed, 70 percent of tornado warnings issued are for storms that never produce tornadoes. It may seem like crying wolf, but think of the 30 percent of warnings that are accurate. And not all tornadoes come from supercells: With names like gustnado and landspout (cousin to the more famous waterspout), these form in unique ways but are considerably weaker than supercell tornadoes.

2. TORNADOES OCCUR ALMOST EVERYWHERE, BUT SOME AREAS SEE MORE TWISTERS THAN OTHERS.

All tornadoes in the U.S. from 1950–2013 based on data from the NOAA Storm Prediction Center. Image credit: Wikipedia Commons // CC BY-SA 4.0

Tornadoes have occurred on every continent except Antarctica. However, the region known as Tornado Alley, in the south-central U.S., has earned that name for a good reason: Though it accounts for just 15 percent of the land in the U.S., it's seen nearly 30 percent of the country's tornadoes, with 16,674 twisters touching down here between 1950 and 2010. It averages 268 tornadoes per year. These tornadoes arise because of a clash between warm moist air from the Gulf of Mexico near the ground, colder air in the upper atmosphere from the west, and a third layer of very warm dry air between the two levels from the southwest that tries to keep the other two at bay.

3. HILLS AND MOUNTAINS CAN STOP A TORNADO—OR STRENGTHEN IT.

Researchers at the University of Alabama at Huntsville have discovered that topography and roughness of the landscape can also influence the power of a tornado. In simulations, the "rougher" the area is, the stronger and wider a tornado can get. Forested areas have a rougher surface than open agricultural areas, and forested mountains are even rougher, according to Kevin Knupp, lead of the Alabama research team. But the picture is more complicated than that, according to his colleague Anthony Lyza, who has found that tornadoes in Alabama are affected by topography. According to Lyza, tornadoes weaken as they proceed up mountains and hills—but they strengthen as they proceed down. And sometimes, regardless of whether a tornado is moving up or down a hill or mountain, the land mass will cause a tornado to dissipate.

4. THE NUCLEAR DAMAGE ON NAGASAKI LED TO A MAJOR SCIENTIFIC DISCOVERY ABOUT TORNADOES.

Tetsuya Fujita was a Japanese meteorologist recruited in 1953 to the University of Chicago. The town he lived in at the end of World War II was the primary target of one of the atomic bombs the U.S. dropped. Due to cloudy conditions, that bomb was dropped on its secondary target—Nagasaki. Fujita’s study of the damage of the nuclear bomb blasts actually led to the discovery of meteorological phenomena called microbursts.

5. THE F-SCALE QUANTIFIES TORNADOES BY THE AMOUNT OF DAMAGE THEY DO ...

Before 1971, all tornadoes were essentially treated the same, regardless of strength, size, path, or damage zone. That year, Fujita released his method of categorizing them: The F-scale, which measures the wind speed of a tornado—indirectly. Because of difficulties getting accurate wind speeds inside a tornado, Fujita looked at how much destruction various tornadoes caused and back-calculated wind speeds based on that. He then created a scale that ranged from F1 to F12, linking together the Beaufort scale of wind strength, long used by mariners and meteorologists, and Mach scale (yes, like jets). An F1 tornado corresponds to a 12 on the Beaufort Scale, and an F12 corresponds to Mach 1. He then added an F0 (40-72 mph) to have a baseline at a level that wouldn’t cause appreciable damage to most structures (influenced by Beaufort’s 0 - calm/no wind), and maxed the tornado part of the scale at F5 (261-318 mph). An F5 is the highest rating given to a tornado, because Fujita believed this to be the theoretical upper limit for how fast winds in a tornado could reach.

An F0 causes light damage to chimneys, breaks tree branches, and damages billboards. An F5 causes incredible damage. It can lift framed houses off their foundations and carry them a considerable distance. It can toss cars more than 300 feet through the air. It can completely debark trees. Even steel-reinforced concrete isn’t safe.

6. … BUT THE F-SCALE IS FLAWED, SO INSTEAD WE USE THE EF-SCALE.

According to meteorologist Charles A. Doswell, there are problems with using the F-scale. “The real-world application of the F-scale has always been in terms of damage, not wind speed," he told Science of the South. "Unfortunately, the relationship between the wind speeds and the damage categories has not been tested in any comprehensive way.”

In 2004 and 2005, dozens of meteorologist and civil engineers collaborated through a research center at Texas Tech University on a more objective scale, which they named the Enhanced Fujita Scale. A year later, the EF-scale went into use in the U.S. The EF-scale has more rigorous and standardized measures of damage; adds additional building and vegetation types; accounts for differences in construction quality; dramatically lowers the wind speeds associated with stronger tornadoes; and expands degrees of damage. Or, as the tornado-chasing character played by Bill Paxton in Twister puts it, “It measures a tornado’s intensity by how much it eats.”

7. BEFORE 1973, MOST RESEARCH ON TORNADOES WAS COMPLETED AFTER THE DAMAGE WAS DONE.

Although radar originated in the 1930s, it wasn't used for the weather until the 1950s. The first radar detection of a tornado occurred in 1953, using a radar designed for naval aircraft. Far more important was the discovery of the tornado vortex signature in 1973, based on observation of a tornado in Union City, Oklahoma. What scientists discovered was that there was a telltale pattern that appeared before the tornado formed.

Before then, researchers had used films, photos, or damage markings for clues. The discovery of the tornado vortex signature led to the modern tornado warning system in the U.S., including a national network of next-generation Doppler radars (NEXRAD, also known as WSR-88D) funded by Congress.

8. A TORNADO VORTEX APPEARS ON RADAR AS RED AND GREEN PIXELS.

The tornado vortex signature appears on the radar as red/yellow (indicating high outbound velocity) and green/blue (inbound velocity) pixels occurring adjacent to each other over a relatively small area. This is also called a velocity couplet, and it’s associated with the mesocyclone, the rotating vortex of air within the supercell. Radar can also be used to detect a hook echo extending from the rear part of the storm, resulting from precipitation wrapping around the backside of the rotating updraft. Terrifyingly, radar can also detect the debris ball from a tornado; objects lofted into the air by a tornado reflect radar waves very well.

9. 2011 WAS ONE OF THE DEADLIEST YEARS FOR TORNADOES ON RECORD.

The tornado season of 2011, known as the Super Outbreak, was one of the most deadly in U.S. history, with 59 tornadoes in 14 states causing 552 fatalities. Most of these deaths occurred in Alabama and Missouri. The three most deadly tornadoes of 2011 were the Joplin, Missouri EF5, which took 159 lives; the Western Alabama EF5, which claimed 72; and the Tuscaloosa-Birmingham EF4, which killed 64. Six of the top 10 deadliest tornadoes that year occurred in Alabama. April 27, 2011, was the deadliest tornado day in the U.S. since March 18, 1925. 

10. PEOPLE WHO LIVE IN MOBILE HOMES ARE MORE AT RISK OF TORNADO-RELATED FATALITY.

From 1985 to 2010, more tornado-related deaths in the Southeast U.S. occurred in mobile homes than any other structure. In the decade before 2011, one-half of all fatalities occurred in mobile homes. Some of this is related to the fact that the Southeast in general has more mobile homes.

11. TORNADOES CAUSE PSYCHOLOGICAL AND EMOTIONAL DAMAGE, TOO. 

A year after the 2011 Super Outbreak, a team of scientists assessed 2000 adolescent survivors of the tornadoes for signs of major depressive episodes (MDE) and post-traumatic stress disorder (PTSD). Roughly 1 in 15 adolescents suffered from PTSD and 1 in 13 developed MDE. Unsurprisingly, both also occurred in greater frequency when a family member had been injured. Nearly one-third of the children surveyed suffered from hyperarousal—a state of tension produced by hormones released during the fight-or-flight reaction—and re-experiencing (or reliving) the event.

12. THE OVERALL TREND IS TOWARD FEWER DEATHS, THANKS TO IMPROVED WARNING SYSTEMS.

Despite the continued occurrence of massive tornadoes, fatalities from these weather phenomena continue to decline. Until the 1930s, the average death toll from tornadoes was well above 200 per year. Since the late 1990s, that average now hovers near 50 deaths per year. Thanks to better technology, models, and data, scientists can increasingly predict—and warn of—conditions that are likely to produce a tornado.

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9 Facts about Physicist Michael Faraday, the 'Father of Electricity'
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A self-taught scientist, Michael Faraday (1791-1867) excelled in chemistry and physics to become one of the most influential thinkers in history. He’s been called the "father of electricity," (Nikola Tesla and Thomas Edison also wear that crown) and his appetite for experimenting knew no bounds. "Nothing is too wonderful to be true, if it be consistent with the laws of nature; and in such things as these, experiment is the best test of such consistency," he wrote. Faraday discovered laws of electromagnetism, invented the first electric motor, and built the first electric generator—paving the way for our mechanized age. Read on for more Faraday facts.

1. HE NEVER HAD A FORMAL SCIENTIFIC EDUCATION.

Born in south London in a working-class family, Faraday earned a rudimentary education in reading, writing, and math. When he turned 14 he was apprenticed to a London bookbinder for the following seven years. In his free time, Faraday read Jane Marcet's Conversations in Chemistry, an 1806 bestseller that explained scientific topics for a general audience.

2. HE WAS A SELF-STARTER.

Like Marcet, Faraday was fascinated by the work of Sir Humphry Davy, a charismatic chemist who had found fame by testing the effects of nitrous oxide on himself. (He let others, including poet Samuel Taylor Coleridge, inhale the gas on the condition that they keep diaries of their thoughts and sensations while high.) In spring 1812, a customer at the bookbindery gave Faraday tickets to see Davy’s upcoming lectures. Faraday compiled his notes from the lectures in a bound volume (the one benefit of his toil at the bookbinder's) and sent the book to Davy, requesting to become his assistant—an unheard-of notion for a tradesman with no university degree. Sensing his intelligence and drive, Davy secured him a job at the Royal Institution, where Davy ran the chemistry lab.

3. HE INVENTED A MOTOR WITH MAGNETS AND MERCURY.

By 1820, other scientists had shown that an electric current produces a magnetic field, and that two electrified wires produce a force on each other. Faraday thought there could be a way to harness these forces in a mechanical apparatus. In 1822, he built a device using a magnet, liquid mercury (which conducts electricity) and a current-carrying wire that turned electrical energy into mechanical energy—in other words, the first electric motor. Faraday noted the success in his journal [PDF]: "Very satisfactory, but make more sensible apparatus."

4. HE ALSO CREATED THE FIRST ELECTRIC GENERATOR.

A decade after his breakthrough with the motor, Faraday discovered that the movement of a wire through a stationary magnetic field can induce an electrical current in the wire—the principle of electromagnetic induction. To demonstrate it, Faraday built a machine in which a copper disc rotated between the two poles of a horseshoe magnet, producing its own power. The machine, later called the Faraday disc, became the first electric generator.

5. HE SHOWED THE PULL OF MAGNETIC FORCE.

In a brilliantly simple experiment (recreated by countless schoolchildren today), Faraday laid a bar magnet on a table and covered it with a piece of stiff paper. Then he sprinkled magnetized iron shavings across the paper, which immediately arranged themselves into semicircular arcs emanating from the ends—the north and south poles—of the magnet. In addition to revealing that magnets still exert pull through barriers, he visualized the pattern of magnetic force in space.

6. YOU CAN VISIT HIS MAGNETIC LABORATORY IN LONDON.

Faraday served in a number of scientific roles at the Royal Institution, an organization dedicated to promoting applied science. Eventually Faraday was appointed as its Fullerian Professor of Chemistry, a permanent position that allowed him to research and experiment to his heart's content. His magnetic laboratory from the 1850s is now faithfully replicated in the Royal Institution's Faraday Museum. It displays many of his world-changing gadgets, including an original Faraday disc, one of his early electrostatic generators, his chemical samples, and a giant magnet.

7. HE POPULARIZED NEW SCIENTIFIC TERMINOLOGY.

Faraday's work was so groundbreaking that no descriptors existed for many of his discoveries. With his fellow scientist William Whewell, Faraday coined a number of futuristic-sounding names for the forces and concepts he identified, such as electrode, anode, cathode, and ion. (Whewell himself coined the word "scientist" in 1834, after "natural philosopher" had become too vague to describe people working in increasingly specialized fields.)

8. PRINCE ALBERT GAVE HIM SOME SWEET REAL ESTATE.

In 1848, the Prince Consort, also known as Queen Victoria's husband Prince Albert, gave Faraday and his family a comfortable home at Hampton Court—not the royal palace, but near it—free of charge, to recognize his contributions to science. The house at 37 Hampton Court Road was renamed Faraday House until he died there on August 25, 1867. Now it's known simply by its street address.

9. HE WAS FEATURED ON THE UNITED KINGDOM'S £20 NOTE.

To honor Faraday's role in the advancement of British science, the Bank of England unveiled a £20 bill with his portrait on June 5, 1991. He joined an illustrious group of Britons with their own notes, including William Shakespeare, Florence Nightingale, and Isaac Newton. By the time it was withdrawn in February 2001, the bank estimated that about 120 million Faraday bills were in circulation (that's more than 2 billion quid).

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4 Expert Tips on How to Get the Most Out of August's Total Solar Eclipse
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As you might have heard, there’s a total solar eclipse crossing the U.S. on August 21. It’s the first total solar eclipse in the country since 1979, and the first coast-to-coast event since June 8, 1918, when eclipse coverage pushed World War I off the front page of national newspapers. Americans are just as excited today: Thousands are hitting the road to stake out prime spots for watching the last cross-country total solar eclipse until 2045. We’ve asked experts for tips on getting the most out of this celestial spectacle.

1. DON’T FRY YOUR EYES—OR BREAK THE BANK

To see the partial phases of the eclipse, you will need eclipse glasses because—surprise!—staring directly at the sun for even a minute or two will permanently damage your retinas. Make sure the glasses you buy meet the ISO 12312-2 safety standards. As eclipse frenzy nears its peak, shady retailers are selling knock-off glasses that will not adequately protect your eyes. The American Astronomical Society keeps a list of reputable vendors, but as a rule, if you can see anything other than the sun through your glasses, they might be bogus. There’s no need to splurge, however: You can order safe paper specs in bulk for as little as 90 cents each. In a pinch, you and your friends can take turns watching the partial phases through a shared pair of glasses. As eclipse chaser and author Kate Russo points out, “you only need to view occasionally—no need to sit and stare with them on the whole time.”

2. DON’T DIY YOUR EYE PROTECTION

There are plenty of urban legends about “alternative” ways to protect your eyes while watching a solar eclipse: smoked glass, CDs, several pairs of sunglasses stacked on top of each other. None works. If you’re feeling crafty, or don’t have a pair of safe eclipse glasses, you can use a pinhole projector to indirectly watch the eclipse. NASA produced a how-to video to walk you through it.

3. GET TO THE PATH OF TOTALITY

Bryan Brewer, who published a guidebook for solar eclipses, tells Mental Floss the difference between seeing a partial solar eclipse and a total solar eclipse is “like the difference between standing right outside the arena and being inside watching the game.”

During totality, observers can take off their glasses and look up at the blocked-out sun—and around at their eerily twilit surroundings. Kate Russo’s advice: Don’t just stare at the sun. “You need to make sure you look above you, and around you as well so you can notice the changes that are happening,” she says. For a brief moment, stars will appear next to the sun and animals will begin their nighttime routines. Once you’ve taken in the scenery, you can use a telescope or a pair of binoculars to get a close look at the tendrils of flame that make up the sun’s corona.

Only a 70-mile-wide band of the country stretching from Oregon to South Carolina will experience the total eclipse. Rooms in the path of totality are reportedly going for as much as $1000 a night, and news outlets across the country have raised the specter of traffic armageddon. But if you can find a ride and a room, you'll be in good shape for witnessing the spectacle.

4. PRESERVE YOUR NIGHT VISION

Your eyes need half an hour to fully adjust to darkness, but the total eclipse will last less than three minutes. If you’ve just been staring at the sun through the partial phases of the eclipse, your view of the corona during totality will be obscured by lousy night vision and annoying green afterimages. Eclipse chaser James McClean—who has trekked from Svalbard to Java to watch the moon blot out the sun—made this rookie mistake during one of his early eclipse sightings in Egypt in 2006. After watching the partial phases, with stray beams of sunlight reflecting into his eyes from the glittering sand and sea, McClean was snowblind throughout the totality.

Now he swears by a new method: blindfolding himself throughout the first phases of the eclipse to maximize his experience of the totality. He says he doesn’t mind “skipping the previews if it means getting a better view of the film.” Afterward, he pops on some eye protection to see the partial phases of the eclipse as the moon pulls away from the sun. If you do blindfold yourself, just remember to set an alarm for the time when the total eclipse begins so you don’t miss its cross-country journey. You'll have to wait 28 years for your next chance.

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