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What is a Polar Vortex?

NASA
NASA

If you’ve turned on the news or stepped outside lately, you’re familiar with the frigid weather that is the polar vortex. (You can see the scope of the vortex in the image above, captured by NOAA’s GOES-East satellite on January 6 as it was entering the U.S.) But just what is this weather phenomenon?

Polar vortexes are basically arctic hurricanes or cyclones. NASA defines them as “a whirling and persistent large area of low pressure, found typically over both North and South poles.” A winter phenomenon, vortexes develop as the sun sets over the pole and temperatures cool, and occur in the middle and upper troposphere and the stratosphere (roughly, between six to 31 miles above the Earth’s surface). In the Northern hemisphere, the vortexes move in a counterclockwise direction. Typically, they dip down over Canada, but according to NBC News, polar vortexes can move into the contiguous U.S. due to warm weather over Greenland or Alaska—which forces denser cold air south—or other weather patterns. But “this very well just may be one of those anomalies where it forces itself southward,” said Frank Giannasca, senior meteorologist at The Weather Channel.

Polar vortexes aren’t rare—in fact, arctic winds do sometimes dip down into the eastern U.S.—but the sheer size of the area affected is. This happens only once in a decade or even longer, according to NBC.

How Cold Is It?

So cold that even the polar bear at Chicago’s Lincoln Park Zoo is being kept indoors (she doesn’t eat seals, so she never developed the layer of blubber her wild brethren use to survive that kind of chill). It’s so cold that Memphis, Tennessee is 20 degrees colder than Anchorage, Alaska. Other areas of North America will experience temperatures of -50 or -60 degrees Fahrenheit, which some have compared to the temperature on Mars (though Boing Boing points out that it's a little more complicated than that).

But thankfully, it’s not going to stick around for long: NASA predicts that the vortex will head back to the pole toward the end of the week.

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Big Questions
Why Does Turkey Make You Tired?
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iStock

Why do people have such a hard time staying awake after Thanksgiving dinner? Most people blame tryptophan, but that's not really the main culprit. And what is tryptophan, anyway?

Tryptophan is an amino acid that the body uses in the processes of making vitamin B3 and serotonin, a neurotransmitter that helps regulate sleep. It can't be produced by our bodies, so we need to get it through our diet. From which foods, exactly? Turkey, of course, but also other meats, chocolate, bananas, mangoes, dairy products, eggs, chickpeas, peanuts, and a slew of other foods. Some of these foods, like cheddar cheese, have more tryptophan per gram than turkey. Tryptophan doesn't have much of an impact unless it's taken on an empty stomach and in an amount larger than what we're getting from our drumstick. So why does turkey get the rap as a one-way ticket to a nap?

The urge to snooze is more the fault of the average Thanksgiving meal and all the food and booze that go with it. Here are a few things that play into the nap factor:

Fats: That turkey skin is delicious, but fats take a lot of energy to digest, so the body redirects blood to the digestive system. Reduced blood flow in the rest of the body means reduced energy.

Alcohol: What Homer Simpson called the cause of—and solution to—all of life's problems is also a central nervous system depressant.

Overeating: Same deal as fats. It takes a lot of energy to digest a big feast (the average Thanksgiving meal contains 3000 calories and 229 grams of fat), so blood is sent to the digestive process system, leaving the brain a little tired.

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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Big Questions
How Are Balloons Chosen for the Macy's Thanksgiving Day Parade?
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Getty Images

The balloons for this year's Macy’s Thanksgiving Day Parade range from the classics like Charlie Brown to more modern characters who have debuted in the past few years, including The Elf On The Shelf. New to the parade this year are Olaf from Disney's Frozen and Chase from Paw Patrol. But how does the retail giant choose which characters will appear in the lineup?

Balloon characters are chosen in different ways. For example, in 2011, Macy’s requested B. Boy after parade organizers saw the Tim Burton retrospective at the Museum of Modern Art. (The company had been adding a series of art balloons to the parade lineup since 2005, which it called the Blue Sky Gallery.) When it comes to commercial balloons, though, it appears to be all about the Benjamins.

First-time balloons cost at least $190,000—this covers admission into the parade and the cost of balloon construction. After the initial year, companies can expect to pay Macy’s about $90,000 to get a character into the parade lineup. If you consider that the balloons are out for only an hour or so, that’s about $1500 a minute.

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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