What Do Pilots Use to Detect Turbulence?

iStock.com/Maravic
iStock.com/Maravic

by Joe Shelton

I think the concept of "turbulence" has gotten a bad reputation.

Just like the wind, turbulence isn't an on or off thing; it's a spectrum.

Step outside one day and a light breeze might be hard to feel, while the next day you might have trouble holding onto your hat because the wind is so strong. But most of the time it's somewhere in between those extremes.

Turbulence is exactly the same. Some days, some places, nothing. Some days it can rattle your teeth (or turn your stomach). But most of the time when turbulence exists, it is light or at worst case slightly annoying.

How do pilots detect turbulence?

Weather forecasts provide estimates when there might be turbulence. The thing to remember is the noun forecast: It's not a guarantee that it will be turbulent, nor is the lack of mention of turbulence in a forecast a guarantee that there won't be turbulence.

In addition, turbulence can be widespread as well as very localized.

I typically detect or expect serious or widespread turbulence as well as local turbulence in one of three of ways:

  • Cumulus clouds: If the clouds are tall and vertical and/or getting taller, then there is a good chance there is turbulence around. The taller the clouds and the faster they are growing, the worse the probable turbulence. Especially in the clouds. The worst example of that would be a thunderstorm. The turbulence within a thunderstorm can tear an aircraft apart.
  • Hot days: Also known as convection, warm and especially hot days mean that the hot air is rising and the reciprocal, cold air is descending. That's a recipe for turbulence. Depending upon the temperature and the aircraft's altitude the turbulence can be irritating or it can be very uncomfortable.
  • Wind: Wind can "tumble," especially downwind of mountains—often for many miles downwind—and it can even be turbulent over mountains, as winds are encouraged to rise following the upwind mountain side.

With very few exceptions, for the most part turbulence isn't dangerous. At least to aircraft. Pilots know how to manage turbulence, often simply by slowing the aircraft's airspeed and/or changing altitude.

However, clear-air turbulence (CAT)—severe turbulence that happens in what otherwise seems to be calm, clear air—can cause injuries to passengers who aren't wearing seat belts or, worse, are walking. And CAT is very difficult to detect until you experience it.

(By the way, clear-air turbulence got its name because although turbulence is often accompanied by clouds, this particular form isn't. Hence the name.)

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

What's the Difference Between a College and a University?

Chinnapong/iStock via Getty Images
Chinnapong/iStock via Getty Images

Going off to college is a milestone in any young adult’s life. The phrase itself conjures up images of newfound independence, exposure to new perspectives, knowledge, and possibly even one or more sips of alcohol.

In America, however, few people use the phrase “going off to university,” or “headed to university,” even if they are indeed about to set off for, say, Harvard University. Why did college become the predominant term for postsecondary education? And is there any difference between the two institutions?

While university appears to be the older of the two terms, dating as far back as the 13th century, schools and students in North America have embraced college to describe most places of higher learning. There is no rigid definition of the words, but there are some general attributes for each. A college is typically a four-year school that offers undergraduate degrees like an associate or a bachelor’s. (Community colleges are often two-year schools.) They don’t typically offer master’s or doctorates, and the size of their student body is typically the smaller of the two.

Universities, on the other hand, tend to offer both undergraduate and graduate programs leading to advanced degrees for a larger group of students. They can also be comprised of several schools—referred to as colleges—under their umbrella. A university could offer both a school of arts and sciences and a school of business. The University of Michigan has a College of Engineering, for example.

While many of these traits are common, they’re not guaranteed. Some colleges can be bigger than universities, some might offer master’s degrees, and so on. To complicate matters further, an institution that fits the criteria of a university might choose to call itself a college. Both Dartmouth College and Boston College qualify as universities but use the college label owing to tradition. Schools may begin as colleges, grow into universities, but retain the original name.

People tend to think of a university as being more prestigious or harder to get into, but there are too many variables to make that determination at a glance. Some colleges might ask more of applicants than universities. Some universities might be smaller than certain colleges. Either one can be public or private.

Things get a little more convoluted abroad. In the UK, students go off to university (or uni) instead of college. The British version of college is typically a two-year program where students either focus on learning one particular skill set (much like a vocational school) or use the time to prepare for exams so that they can advance to university. Language matters, too; in Spanish, colegio usually refers to high school.

While the terms aren’t strictly interchangeable, there is enough of a difference between the two to try and make the distinction. Keep in mind that some states, like New Jersey, have rules about how institutions label themselves. There, a university has to have at least three fields of graduate study leading to advanced degrees.

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Why Do We Eat Candy on Halloween?

Jupiterimages/iStock via Getty Images
Jupiterimages/iStock via Getty Images

On October 31, hordes of children armed with Jack-o'-lantern-shaped buckets and pillow cases will take to the streets in search of sugar. Trick-or-treating for candy is synonymous with Halloween, but the tradition had to go through a centuries-long evolution to arrive at the place it is today. So how did the holiday become an opportunity for kids to get free sweets? You can blame pagans, Catholics, and candy companies.

Historians agree that a Celtic autumn festival called Samhain was the precursor to modern Halloween. Samhain was a time to celebrate the last harvest of the year and the approach of the winter season. It was also a festival for honoring the dead. One way Celtics may have appeased the spirits they believed still walked the Earth was by leaving treats on their doorsteps.

When Catholics infiltrated Ireland in the 1st century CE, they rebranded many pagan holidays to fit their religion. November 1 became the “feasts of All Saints and All Souls," and the day before it was dubbed "All-Hallows'-Eve." The new holidays looked a lot different from the original Celtic festival, but many traditions stuck around, including the practice of honoring the dead with food. The food of choice for Christians became "soul cakes," small pastries usually baked with expensive ingredients and spices like currants and saffron.

Instead of leaving them outside for passing ghosts, soul cakes were distributed to beggars who went door-to-door promising to pray for souls of the deceased in exchange for something to eat. Sometimes they wore costumes to honor the saints—something pagans originally did to avoid being harassed by evil spirits. The ritual, known as souling, is believed to have planted the seeds for modern-day trick-or-treating.

Souling didn't survive the holiday's migration from Europe to the United States. In America, the first Halloween celebrations were a way to mark the end-of-year harvest season, and the food that was served mainly consisted of homemade seasonal treats like caramel apples and mixed nuts. There were no soul cakes—or candies, for that matter—to be found.

It wasn't until the 1950s that trick-or-treating gained popularity in the U.S. Following the Great Depression and World War II, the suburbs were booming, and people were looking for excuses to have fun and get to know their neighbors. The old practice of souling was resurrected and made into an excuse for kids to dress up in costumes and roam their neighborhoods. Common trick-or-treat offerings included nuts, coins, and homemade baked goods ("treats" that most kids would turn their noses up at today).

That changed when the candy companies got their hands on the holiday. They had already convinced consumers that they needed candy on Christmas and Easter, and they were looking for an equally lucrative opportunity to market candy in the fall. The new practice of trick-or-treating was almost too good to be true. Manufacturers downsized candies into smaller, bite-sized packages and began marketing them as treats for Halloween. Adults were grateful to have a convenient alternative to baking, kids loved the sweet treats, and the candy companies made billions.

Today, it's hard to imagine Halloween without Skittles, chocolate bars, and the perennial candy corn debates. But when you're digging through a bag or bowl of Halloween candy this October, remember that you could have been having eating soul cakes instead.

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