Why Do Tornados Frequently Hit Oklahoma City?


Oklahoma City holds the dubious distinction of being the unofficial Tornado Capital of the United States. The U.S. city has endured more tornados than any other—149 officially recorded since 1890, as far back as National Oceanic and Atmospheric Administration records go.

The Oklahoma City metro area has been ravaged by no less than six tornados in the past month (five recorded this past week alone in and around El Reno, OK), which altogether have caused almost three dozen deaths and major property damage. Moore, Oklahoma—a suburb just 10 miles south of Oklahoma City—got slammed by no less than five major tornados since 1998, two of them categorized as mighty EF5s: the devastating tornado that struck last month, and one in May of 1999. With winds clocked at 318 miles per hour, the latter is considered to be the strongest tornado ever recorded worldwide.

Why does the Big Friendly steal the thunder?

The answer is complicated, because there is still a lot we don’t know about the inner workings of tornados. Where they touch down is not an exact science, and much of the research meteorological scientists have conducted has shown that twisters don’t seem to be very picky about where they show up and when. Pure coincidence may be all we can blame.

What we do know is that the unique geography of the continental United States makes it more susceptible to tornados than the rest of the world, particularly in the central plains region the media refers to as “Tornado Alley”—which plays doormat to roughly a quarter of the strongest tornados recorded. Tornados are the spawn of the lurid meteorological embrace of cool, dry Rocky Mountain air moving southeast and warm, humid Gulf air moving northwest that meet over the country’s midsection, most notably over that swath of the plains that extends from Iowa south to northern Texas.

The rotating mix of air currents forms giant supercell thunderstorms that tend to breed tornados, and Oklahoma City appears to be smack dab in the middle of it. The local terrain certainly helps—there aren’t many large bodies of water nor are there mountainous regions in the area that can complicate tornado formation. Large rivers, great lakes or proximity to the ocean can potentially cool warm air, which may ease the severity of thunderstorms that form downwind of these bodies of water. Mountains too can have a similar deterring effect. But these two landscape characteristics do not absolutely protect a region from tornados, as many myths have perpetuated. Tornados recorded in places like Maine, Washington state and the New York City area are stark evidence of that.

The NOAA estimates that there are 1300 tornados in the United States on average each year, more than anywhere else in the world. Around 55 of them roar through the state of Oklahoma.

Other Tornado Hotbeds

Tornados have been reported all over the world, and some of the world's most tornado-prone areas are in regions with similar combinations of geographical, topographical and meterological conditions to those of Tornado Alley.

Dixie Alley
The lower Mississippi valley from Texas east through Louisiana, Alabama, Mississippi, Georgia, and South Carolina, and as far north as Missouri, Tennessee, and Kentucky, has lately been seeing a lot of tornado activity. Tornados in Dixie Alley tend to occur in the fall when the jet stream from the Gulf pushing warm, moist air is more powerful, and often come at night and/or wrapped in blinding rain, making them more difficult to detect and thus potentially more deadly than Tornado Alley storms. Notable Dixie Alley twisters include the 2011 storms that hit Tuscaloosa, Alabama (EF4) and Joplin, Missouri (EF5)—considered the deadliest tornado the United States has ever endured.

According to NOAA data, between 1991 and 2012, Florida averaged 66 tornados annually, behind just Texas (155) and Kansas (96). The Sunshine State, however, gets more press for its susceptibility to destructive tropical storms and hurricanes, as well as frequent thunderstorms. All of these can and often do spawn tornados when they move over the peninsula. They don’t get much notice because they are typically weak funnels.

Serranias del Burro
The Coahuila state of Mexico is home to the Serranias del Burro, the mountainous region that makes up the northern lobe of the Sierra Madre Oriental mountain range. It is prone to supercell thunderstorms that spawn tornados similar to those observed in Tornado Alley. Typically though, these storms cross the border (over the Rio Grande) into the U.S. and produce tornados there.

Canadian Tornado Alley
Tornados occur most frequently in the strip of southern Canadian provinces that border the United States. Provinces east of the Canadian Rockies like Alberta, Manitoba, and Saskatchewan, which can still get a breath of that warm Gulf air, are susceptible. Ontario gets another kind of licking, particularly in the south in the summertime, due to the cool breezes that blow off the Great Lakes and interact with warm summer air.

Nestled at the head of the Bay of Bengal, this sea-level southeast Asian country is prone to tornados and cyclones much like Dixie Alley and Florida. A tornado that hit the cities of Daulatpur and Saturia in 1989 is widely considered to be the deadliest tornado in history, having killed as many as 1300 people. Bangladesh has the unfortunate distinction of being both one of the most densely populated countries in the world, and one of the most tornado-prone—so when tornados strike, they can be far more deadly than in other areas.

Elsewhere in the world, Argentina, South Africa, and Russia are also notable spots for tornado outbreaks, but lack of organized record-keeping makes it hard to determine the extent of their frequency.

Big Questions
Why Do Onions Make You Cry?

The onion has been traced back as far as the Bronze Age and was worshipped by the Ancient Egyptians (and eaten by the Israelites during their bondage in Egypt). Onions were rubbed over the muscles of Roman gladiators, used to pay rent in the Middle Ages, and eventually brought to the Americas, where today we fry, caramelize, pickle, grill, and generally enjoy them.

Many of us burst into tears when we cut into one, too. It's the price we pay for onion-y goodness. Here's a play-by-play breakdown of how we go from grabbing a knife to crying like a baby:

1. When you cut into an onion, its ruptured cells release all sorts of goodies, like allinase enzymes and amino acid sulfoxides. The former breaks the latter down into sulfenic acids.

2. The sulfenic acids, unstable bunch that they are, spontaneously rearrange into thiosulfinates, which produce a pungent odor and at one time got the blame for our tears. The acids are also converted by the LF-synthase enzyme into a gas called syn-propanethial-S-oxide, also known as the lachrymatory factor (or the crying factor).

3. Syn-propanethial-S-oxide moves through the air and reaches our eyes. The first part of the eye it meets, the cornea, is populated by autonomic motor fibers that lead to the lachrymal glands. When syn-propanethial-S-oxide is detected, all the fibers in the cornea start firing and tell the lachrymal glands to wash the irritant away.

4. Our eyes automatically start blinking and producing tears, which flushes the irritant away. Of course, our reaction to burning eyes is often to rub them, which only makes things worse since our hands also have some syn-propanethial-S-oxide on them.

It only takes about 30 seconds to start crying after you make the first cut; that's the time needed for syn-propanethial-S-oxide formation to peak.


The onion's relatives, like green onions, shallots, leeks and garlic, also produce sulfenic acids when cut, but they generally have fewer (or no) LF-synthase enzymes and don't produce syn-propanethial-S-oxide.


Since I usually go through a good deal of onions while cooking at home, I've been road testing some of the different methods the internet suggests for reducing or avoiding the effects of the lachrymatory factor. Here's what I tried:

Method #1: Chill or slightly freeze the onions before cutting, the idea being that this will change the chemical reactions and reduce the gas that is released.
Result: The onion from the fridge has me crying just as quickly as room temperature ones. The one that was in a freezer for 30 minutes leaves me dry-eyed for a bit, but by the time I'm done dicing my eyes start to burn a little.

Method #2: Cut fast! Get the chopping over with before the gas reaches your eyes.
Result: Just hacking away at the onion, I get in the frying pan without so much as a sting in my eyes. The onion looks awful, though. Doing a proper dice, I take a little too long and start tearing up. If you don't mind a mangled onion, this is the way to go.

Method #3: Put a slice of bread in your mouth, and cut the onion with most of the bread sticking out to "catch" the fumes.
Result: It seems the loaf of bread I have has gone stale. I stop the experiment and put bread on my shopping list.

Method #4: Chew gum while chopping. It keeps you breathing through your mouth, which keeps the fumes away from your eyes.
Result: This seems to work pretty well as long as you hold your head in the right position. Leaning toward the cutting board or looking right down at the onion puts your eyes right in the line of fire again.

Method #5: Cut the onions under running water. This prevents the gas from traveling up into the eyes.
Result: An onion in the sink is a hard onion to cut. I think Confucius said that. My leaky Brita filter is spraying me in the face and I'm terrified I'm going to cut myself, but I'm certainly not crying.

Method #6: Wear goggles.
Result: In an effort to maintain my dignity, I try my eyeglasses and sunglasses first. Neither do me any good. The ol' chemistry lab safety glasses make me look silly, but help a little more. I imagine swim goggles would really do the trick, but I don't have any.

Method #7: Change your onion. "Tear free" onions have been developed in the UK via special breeding and in New Zealand via "gene silencing" techniques.
Result: My nearest grocery store, Whole Foods, doesn't sell genetically modified produce or onions from England. Tonight, we eat leeks!

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Big Questions
What is Mercury in Retrograde, and Why Do We Blame Things On It?

Crashed computers, missed flights, tensions in your workplace—a person who subscribes to astrology would tell you to expect all this chaos and more when Mercury starts retrograding for the first time this year on Friday, March 23. But according to an astronomer, this common celestial phenomenon is no reason to stay cooped up at home for weeks at a time.

"We don't know of any physical mechanism that would cause things like power outages or personality changes in people," Dr. Mark Hammergren, an astronomer at Chicago's Adler Planetarium, tells Mental Floss. So if Mercury doesn’t throw business dealings and relationships out of whack when it appears to change direction in the sky, why are so many people convinced that it does?


Mercury retrograde—as it's technically called—was being written about in astrology circles as far back as the mid-18th century. The event was noted in British agricultural almanacs of the time, which farmers would read to sync their planting schedules to the patterns of the stars. During the spiritualism craze of the Victorian era, interest in astrology boomed, with many believing that the stars affected the Earth in a variety of (often inconvenient) ways. Late 19th-century publications like The Astrologer’s Magazine and The Science of the Stars connected Mercury retrograde with heavy rainfall. Characterizations of the happening as an "ill omen" also appeared in a handful of articles during that period, but its association with outright disaster wasn’t as prevalent then as it is today.

While other spiritualist hobbies like séances and crystal gazing gradually faded, astrology grew even more popular. By the 1970s, horoscopes were a newspaper mainstay and Mercury retrograde was a recurring player. Because the Roman god Mercury was said to govern travel, commerce, financial wealth, and communication, in astrological circles, Mercury the planet became linked to those matters as well.

"Don’t start anything when Mercury is retrograde," an April 1979 issue of The Baltimore Sun instructed its readers. "A large communications organization notes that magnetic storms, disrupting messages, are prolonged when Mercury appears to be going backwards. Mercury, of course, is the planet associated with communication." The power attributed to the event has become so overblown that today it's blamed for everything from digestive problems to broken washing machines.


Though hysteria around Mercury retrograde is stronger than ever, there's still zero evidence that it's something we should worry about. Even the flimsiest explanations, like the idea that the gravitational pull from Mercury influences the water in our bodies in the same way that the moon controls the tides, are easily deflated by science. "A car 20 feet away from you will exert a stronger pull of gravity than the planet Mercury does," Dr. Hammergren says.

To understand how little Mercury retrograde impacts life on Earth, it helps to learn the physical process behind the phenomenon. When the planet nearest to the Sun is retrograde, it appears to move "backwards" (east to west rather than west to east) across the sky. This apparent reversal in Mercury's orbit is actually just an illusion to the people viewing it from Earth. Picture Mercury and Earth circling the Sun like cars on a racetrack. A year on Mercury is shorter than a year on Earth (88 Earth days compared to 365), which means Mercury experiences four years in the time it takes us to finish one solar loop.

When the planets are next to one another on the same side of the Sun, Mercury looks like it's moving east to those of us on Earth. But when Mercury overtakes Earth and continues its orbit, its straight trajectory seems to change course. According to Dr. Hammergren, it's just a trick of perspective. "Same thing if you were passing a car on a highway, maybe going a little bit faster than they are," he says. "They're not really going backwards, they just appear to be going backwards relative to your motion."

Embedded from GIFY

Earth's orbit isn't identical to that of any other planet in the solar system, which means that all the planets appear to move backwards at varying points in time. Planets farther from the Sun than Earth have even more noticeable retrograde patterns because they're visible at night. But thanks to astrology, it's Mercury's retrograde motion that incites dread every few months.

Dr. Hammergren blames the superstition attached to Mercury, and astrology as a whole, on confirmation bias: "[Believers] will say, 'Aha! See, there's a shake-up in my workplace because Mercury's retrograde.'" He urges people to review the past year and see if the periods of their lives when Mercury was retrograde were especially catastrophic. They'll likely find that misinterpreted messages and technical problems are fairly common throughout the year. But as Dr. Hammergren says, when things go wrong and Mercury isn't retrograde, "we don't get that hashtag. It's called Monday."

This story originally ran in 2017.


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