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Jeff Swensen, Getty Images
Jeff Swensen, Getty Images

Why Do We Use a Groundhog to Forecast the Weather?

Jeff Swensen, Getty Images
Jeff Swensen, Getty Images

It's only been in the past 60 or so years that humans have been able to rely on television meteorologists for weather predictions. Before Al Roker, the Babylonians looked at cloud formations; in 300 BCE, the Chinese had a calendar broken into 24 festivals, each with its own unique weather patterns.

Today we use satellites and other costly equipment to gauge our environment, examining changes in the atmosphere and running sophisticated computer models. And sometimes, we just stare at a groundhog.

Every February 2, a doughy rodent named Punxsutawney Phil briefly emerges from his winter hibernation to have a look around. If he sees his shadow, that means there will be six more weeks of winter. If he doesn't, we can assume that warm weather is looming.

The ritual has been carried out in Punxsutawney, Pennsylvania every year since 1887. Relying on Phil is actually not much better than flipping a coin—he's right an estimated 64.4 percent of the time—but clearly someone at one time believed a groundhog had predictive abilities. Who? And why?

To understand Phil's current status, it helps to know that superstition and weather have had a long association. Observers of the Christian holiday Candlemas, for example, received candles blessed by clergymen. If the skies were cloudy that day, warm weather was imminent; if the sun was out, winter would persist.

In Europe, the idea that winter's duration could be foretold was carried over to animal behavior. Hibernating animals like bears, marmots, and hedgehogs were observed to see when they'd emerge from their dens. 

In Germany, the weather was anticipated by badgers. When Germans began settling in Pennsylvania, however, badgers weren't so readily available: The easiest hibernating animal to locate was the groundhog. In 1887, a newspaper editor began circulating the idea that one groundhog in particular, Punxsutawney Phil, was a meteorological wonder. Before long, the entire country became preoccupied with Phil’s prognosticating, and an annual tradition was born.

Phil isn't the only one in the business of long-range forecasting. The Old Farmer's Almanac, a yearly digest of upcoming weather patterns for large geographical areas, is prepared up to 18 months in advance: Its editors claim an 80 percent accuracy rate, though some meteorologists dispute the viability of assessing weather more than two weeks out.

Last year, Phil "predicted" six more weeks of winter. It turned out to be the second-warmest February on record.

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Why Is the American Flag Displayed Backwards on Military Uniforms?
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In 1968, famed activist Abbie Hoffman decided to crash a meeting of the House Un-American Activities Committee in Washington by showing up in a shirt depicting the American flag. Hoffman was quickly surrounded by police, who ripped his shirt off and arrested him for desecration of the Red, White, and Blue.

Hoffman’s arrest is notable today because, while it might be unpatriotic to some, wearing the American flag, burning it, or otherwise disrespecting it is not a violation of any federal law. In 1989, the Supreme Court ruled that it would be unconstitutional to prosecute any such action. Still, Americans have very fervent and strict attitudes toward displaying the flag, a longstanding symbol of our country’s freedom. According to the U.S. Flag Code, which was first published in 1923, you shouldn’t let the flag touch the ground or hang it upside-down. While there’s no express prohibition about reversing the image, it’s probably a safe bet you shouldn’t do that, either.

Yet branches of the U.S. military are often spotted with a seeming mirror reflection of the flag on their right shoulder. If you look at a member in profile, the canton—the rectangle with the stars—is on the right. Isn’t that backwards? Shouldn’t it look like the flag on the left shoulder?

The American flag appears on a military uniform
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Not really. The flag is actually facing forward, and it’s not an optical illusion.

When a service member marches or walks forward, they assume the position of a flagpole, with the flag sewn on their uniform meant to resemble a flag flapping in the breeze. With the canton on the right, the flag would be fluttering behind them. If it were depicted with the canton on the left, the flag would be flying backward—as though it had been hung by the stripes instead of the stars nearest to the pole. The position of the flag is noted in Army Regulation 670-1, mandating the star field should face forward. The official term for this depiction is “reverse side flag.”

As for Hoffman: His conviction was overturned on appeal. In 1970, while at a flag-themed art show in New York, he was invited to get up and speak. He wore a flag shirt for the occasion.

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What Causes Sinkholes?
Mark Ralston/AFP/Getty Images
Mark Ralston/AFP/Getty Images

This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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