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Why Does Snow Squeak When You Step On It?

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With Winter Storm Jonas expected to dump tons of snow on a large swath of the East Coast over the next few days, you might be trying to figure out if you have enough bread, milk, and eggs (and booze!) at home to get through the weekend. We’re also pondering another important question—why is snow, which is so quiet when it’s falling out of the sky, so loud on the ground, squeaking, creaking, and crunching under our boots? (If you’re not from a snowy part of the country, you can hear what we’re talking about in the video below).

Snow is made up of ice crystals. While ice is a solid, it actually has a thin (as in, a few nanometers) quasi-liquid layer (QLL) on its surface. Michael Faraday, better known for his work on magnetism and electrochemistry, first suggested this idea in the 1850s. While scientists have confirmed it since then, the origins and many of the characteristics of the QLL are unclear.

One thing we do know, though, is that the thickness of the QLL depends on temperature. When snow is warmer, the QLL around all those ice crystals is softer. When you step on the snow, the National Snow and Ice Data Center explains, you compress the crystals, but the liquid allows them to quietly slide past each other. When snow is colder and the QLL is stronger, there’s more friction between the crystals, and they don’t slide so easily. When you step on colder snow, the crystals rub against each other and also break, making that familiar squeaking sound.

Around 14 degrees Fahrenheit seems to the dividing line between squeaky and non-squeaky snow. Temperatures in the region getting hit by Jonas will be well above that through the weekend, so we’re probably in for a quiet storm.

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Big Questions
What Are Curlers Yelling About?
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WANG ZHAO/AFP/Getty Images

Curling is a sport that prides itself on civility—in fact, one of its key tenets is known as the “Spirit of Curling,” a term that illustrates the respect that the athletes have for both their own teammates and their opponents. But if you’re one of the millions of people who get absorbed by the sport once every four years, you probably noticed one quirk that is decidedly uncivilized: the yelling.

Watch any curling match and you’ll hear skips—or captains—on both sides barking and shouting as the 42-pound stone rumbles down the ice. This isn’t trash talk; it’s strategy. And, of course, curlers have their own jargon, so while their screams won’t make a whole lot of sense to the uninitiated, they could decide whether or not a team will have a spot on the podium once these Olympics are over.

For instance, when you hear a skip shouting “Whoa!” it means he or she needs their teammates to stop sweeping. Shouting “Hard!” means the others need to start sweeping faster. If that’s still not getting the job done, yelling “Hurry hard!” will likely drive the point home: pick up the intensity and sweep with downward pressure. A "Clean!" yell means put a brush on the ice but apply no pressure. This will clear the ice so the stone can glide more easily.

There's no regulation for the shouts, though—curler Erika Brown says she shouts “Right off!” and “Whoa!” to get her teammates to stop sweeping. And when it's time for the team to start sweeping, you might hear "Yes!" or "Sweep!" or "Get on it!" The actual terminology isn't as important as how the phrase is shouted. Curling is a sport predicated on feel, and it’s often the volume and urgency in the skip’s voice (and what shade of red they’re turning) that’s the most important aspect of the shouting.

If you need any more reason to make curling your favorite winter sport, once all that yelling is over and a winner is declared, it's not uncommon for both teams to go out for a round of drinks afterwards (with the winners picking up the tab, obviously). Find out how you can pick up a brush and learn the ins and outs of curling with our beginner's guide.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Why You Should Never Take Your Shoes Off On an Airplane
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What should be worn during takeoff?

Tony Luna:

If you are a frequent flyer, you may often notice that some passengers like to kick off their shoes the moment they've settled down into their seats.

As an ex-flight attendant, I'm here to tell you that it is a dangerous thing to do. Why?

Besides stinking up the whole cabin, footwear is essential during an airplane emergency, even though it is not part of the flight safety information.

During an emergency, all sorts of debris and unpleasant ground surfaces will block your way toward the exit, as well as outside the aircraft. If your feet aren't properly covered, you'll have a hard time making your way to safety.

Imagine destroying your bare feet as you run down the aisle covered with broken glass, fires, and metal shards. Kind of like John McClane in Die Hard, but worse. Ouch!

Bruce Willis stars in 'Die Hard' (1988)
20th Century Fox Home Entertainment

A mere couple of seconds delay during an emergency evacuation can be a matter of life and death, especially in an enclosed environment. Not to mention the entire aircraft will likely be engulfed in panic and chaos.

So, the next time you go on a plane trip, please keep your shoes on during takeoff, even if it is uncomfortable.

You can slip on a pair of bathroom slippers if you really need to let your toes breathe. They're pretty useless in a real emergency evacuation, but at least they're better than going barefoot.

This post originally appeared on Quora. Click here to view.

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