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.

Why Do Students Get Summers Off?

Iam Anupong/iStock via Getty Images
Iam Anupong/iStock via Getty Images

It’s commonly believed that school kids started taking summers off in the 19th century so that they’d have time to work on the farm. Nice as that story is, it isn’t true. Summer vacation has little to do with tilling fields and more to do with sweaty, rich city kids playing hooky—and their sweaty, rich parents.

Before the Civil War, farm kids never had summers off. They went to school during the hottest and coldest months and stayed home during the spring and fall, when crops needed to be planted and harvested. Meanwhile, city kids hit the books all year long—summers included. In 1842, Detroit’s academic year lasted 260 days.

But as cities got denser, they got hotter. Endless lanes of brick and concrete transformed urban blocks into kilns, thanks to what was known as the “urban heat island effect.” That’s when America’s swelling middle and upper class families started hightailing it to the cooler countryside. And that caused a problem. School attendance wasn’t mandatory back then, and classrooms were being left half-empty each summer. Something had to give.

Legislators, in one of those if-you-can’t-beat-‘em-join-‘em moments, started arguing that kids should get summers off anyway. It helped that, culturally, leisure time was becoming more important. With the dawn of labor unions and the eight-hour workday, working adults were getting more time to themselves than ever before. Advocates for vacation time also argued (incorrectly) that the brain was a muscle, and like any muscle, it could suffer injuries if overused. From there, they argued that students shouldn’t go to school year-round because it could strain their brains. To top it off, air conditioning was decades away, and city schools during summertime were miserable, half-empty ovens.

So by the turn of the century, urban districts had managed to cut about 60 schooldays from the most sweltering part of the year. Rural schools soon adopted the same pattern so they wouldn’t fall behind. Business folks obviously saw an opportunity here. The summer vacation biz soon ballooned into what is now one of the country’s largest billion-dollar industries.

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Where Did the Term Brownie Points Come From?

bhofack2/iStock via Getty Images
bhofack2/iStock via Getty Images

In a Los Angeles Times column published on March 15, 1951, writer Marvin Miles observed a peculiar phrase spreading throughout his circle of friends and the social scene at large. While standing in an elevator, he overheard the man next to him lamenting “lost brownie points.” Later, in a bar, a friend of Miles's who had stayed out too late said he would never “catch up” on his brownie points.

Miles was perplexed. “What esoteric cult was this that immersed men in pixie mathematics?” he wrote. It was, his colleagues explained, a way of keeping “score” with their spouses, of tallying the goodwill they had accrued with the “little woman.”

Over the decades, the phrase brownie points has become synonymous with currying favor, often with authority figures such as teachers or employers. So where exactly did the term come from, and what happens when you “earn” them?

The most pervasive explanation is that the phrase originated with the Brownies, a subsect of the Girl Scouts who were encouraged to perform good deeds in their communities. The Brownies were often too young to be official Girl Scouts and were sometimes the siblings of older members. Originally called Rosebuds in the UK, they were renamed Brownies when the first troops were being organized in 1916. Sir Robert Baden-Powell, who had formed the Boy Scouts and was asked to name this new Girl Scout division, dubbed them Brownies after the magical creatures of Scottish folklore that materialized to selflessly help with household chores.

But the Brownies are not the only potential source. In the 1930s, kids who signed up to deliver magazines like The Saturday Evening Post and Ladies' Home Journal from Curtis Publishing were eligible for vouchers labeled greenies and brownies that they could redeem for merchandise. They were not explicitly dubbed brownie points, but it’s not hard to imagine kids applying a points system to the brownies they earned.

The term could also have been the result of wartime rationing in the 1940s, where red and brown ration points could be redeemed for meats.

The phrase didn’t really seem to pick up steam until Miles's column was published. In this context, the married men speaking to Miles believed brownie points could be collected by husbands who remembered birthdays and anniversaries, stopped to pick up the dry cleaning, mailed letters, and didn’t spend long nights in pubs speaking to newspaper columnists. The goal, these husbands explained, was never to get ahead; they merely wanted to be considered somewhat respectable in the eyes of their wives.

Later, possibly as a result of its usage in print, grade school students took the phrase to mean an unnecessary devotion to teachers in order to win them over. At a family and faculty meeting at Leon High in Tallahassee, Florida, in 1956, earning brownie points was said to be a serious problem. Also called apple polishing, it prompted other students in class to shame their peers for being friendly to teachers. As a result, some were “reluctant to be civil” for fear they would be harassed for sucking up.

In the decades since that time, the idiom has become attached to any act where goodwill can be expected in return, particularly if it’s from someone in a position to reward the act with good grades or a promotion. As for Miles: the columnist declared his understanding of brownie points came only after a long night of investigation. Arriving home late, he said, rendered him “pointless.”

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