Death Valley National Park is located in Eastern California. During the summer it is one of the hottest places on Earth where the highest recorded temperature of it reached 54.4°C or 130F.However, whenever the hottest temperature gets updated a historical artifact claiming that the hottest temperature it reached is actually 57°C or 134F. This was assessed and is claimed as an observer error.

Death Valley National Park

The Automated Surface Observing Systems (asos) is what we use to collect data of temperatures, precipitation, cloud cover, wind speed, and pressure.We have been using the asos since the mid-90s and on average these send data reports every 20 minutes.Official weather-taking themometers are different from the ones that people install in their houses. These official thermometers need to be shielded from external factors that can influence the temperature outcome.

How We Record Temperatures

Our systems for measuring temperature are more accurate now with all the automated readings and less of the "to decipher" handwritten records. Although there is still a chance for an anomaly to occur, it's pretty rare.What happens now is that due to the temperatures rising worldwide and with the data we have, we cannot and should not ignore the wrath of intensified weather.

Why Temperatures Matter

In Death Valley and beyond, the quantity of horrifically hot days is what actually matters—not just one blip recorded a century ago.

Stashed ideas

Some records are a little trickier to define than others, though. Take Death Valley in California as an example. This is the hottest, driest, and lowest national park in the US and is no stranger to intense heat. High temperature averages are 100 degrees Fahrenheit and above for at least a third of the year, and just last week produced the highest daily average temperature observed on the planet <a dir="ltr" href="https://www.washingtonpost.com/weather/2021/07/12/death-valley-record-heat-earth/" rel="noreferrer noopener">at 118.1 degrees </a>. On Friday, July 9, the high temperature reached a scorching 130 degrees Fahrenheit, one of the highest recorded temperatures of all time.

But every time Death Valley has a wildly high temperature, a weird historical artifact pops up—the one time in 1913 that the temperature <a dir="ltr" href="https://www.nbclosangeles.com/weather-news/death-valley-world-record-temperature-heat/2394047/" rel="noreferrer noopener">was recorded as 134 degrees Fahrenheit </a>. Over a century ago, US Weather Bureau observer Oscar Denton measured a week-long string of <a dir="ltr" href="https://www.wunderground.com/blog/weatherhistorian/an-investigation-of-death-valleys-134f-world-temperature-record.html" rel="noreferrer noopener">suspiciously high temperatures </a>in Death Valley’s Greenland Ranch. If you look at the other temperatures recorded nearby, <a dir="ltr" href="https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/10/25/new-analysis-shreds-claim-that-death-valley-recorded-earths-hottest-temperature-in-1913/" rel="noreferrer noopener">this recording stood out like a sore thumb </a>—temperatures creeping into the high 120’s didn’t start reappearing until the late 1990s when the IPCC had <a dir="ltr" href="https://www.newscientist.com/article/dn9912-timeline-climate-change/" rel="noreferrer noopener">begun to recognize global warming </a>.

While that reading is still technically listed as the world’s hottest temperature ever recorded, some argue that this month’s high is likely a more realistic record.

“If Friday’s observation passes an investigation (instrument calibration, etc.) then, yes, this is a new reliably measured global extreme heat record,” weather records expert Christopher Burt told <a dir="ltr" href="https://yaleclimateconnections.org/2021/07/death-valley-california-breaks-the-all-time-world-heat-record-for-the-second-year-in-a-row/" rel="noreferrer noopener">Yale Climate Connections </a>. That’s because it was shockingly tricky to get accurate temperature readings in the past, which makes it difficult to know which temperatures are legitimate and which aren’t.

Like many modern-day data capturing methods, temperatures (as well as precipitation, cloud cover, wind speed and pressure) have been collected automatically in <a dir="ltr" href="https://www.ncei.noaa.gov/products/automated-surface-weather-observing-systems" rel="noreferrer noopener">Automated Surface Observing Systems </a>since the mid-90s, explains Jon Erdman, a senior meteorologist at the Weather Channel. There are over 900 of these systems throughout the US, and on average report weather data around every 20 minutes.

But the thermometer that records temperatures all day every day from stations around the world isn’t exactly like the ones you might have outside your house, Erdman adds. Official weather-taking thermometers need to be shielded from the sun and wind, and have what looks like little lampshades on them so that they can measure the actual surface temperature without being influenced by other sources.

“If you don’t shield the thermometer from direct sunlight, it’s going to heat up more,” he says. So if you’re ever wondering why your personal thermometer might show a bit more heat than the Weather Channel is showing, that could be a reason why.

Scientists have been shielding their thermometers since the late 1800s, starting with the Stevenson screen, which looked a bit like a <a dir="ltr" href="https://www.weatheronline.co.uk/reports/wxfacts/The-Stevenson-Screen.htm" rel="noreferrer noopener">little white birdhouse or cabinet and held a variety of weather-investigating </a>tools. Like today’s setup, this contraption protected the thermometer from the elements to just get surface temperature.

In the 21st century, the setup hasn’t changed much—the key difference is just how involved humans used to be. “What you’ll see in these [historical] measurements is literally hand-written measures of every single day, going and seeing what that thermometer says,” says Karen McKinnon, a professor of statistics and sustainability at UCLA.

So, occasional errors are completely within expectation. But how could a person record such a high temperature by accident? From a technological standpoint, in a place as toasty as Death Valley, even a little bit of direct sunlight or scorching hot sand brushing against the meter could rack up some extra degrees, Erdman says.

McKinnon has also found<a dir="ltr" href="https://dash.harvard.edu/handle/1/32097099" rel="noreferrer noopener">in her research that people often round up to preferentially </a>chosen numbers rather than be uncertain about the exact temperature. Then, when it comes to the Global Historical Climate Network Daily database, everything gets rounded up to the closest 0.1 degree Celsius, despite the level of precision it was initially recorded. In her findings, 63 percent of temperature samples were biased by this double-rounding.

In a <a dir="ltr" href="https://www.wunderground.com/blog/weatherhistorian/an-investigation-of-death-valleys-134f-world-temperature-record.html" rel="noreferrer noopener">lengthy 2016 take-down </a>of the record, geographer William T. Reid and weather historian Christopher Burt also raised concerns about the observers’ credibility to accurately record temperatures, exaggerating the temperature beyond what anyone could explain meteorologically.

“Things can always go wrong,” McKinnon says. “People can misrecord temperatures, which is probably the most likely situation”

This isn’t the first time a global heat record has been challenged. Back in 2012, a reading of <a dir="ltr" href="https://www.eurekalert.org/pub_releases/2012-09/asu-wht091112.php" rel="noreferrer noopener">136.4 degrees Fahrenheit in El Azizia, Libya on Sept. 13, 1922, was removed </a>from its record-holding spot after an international team found five major concerns with the recording, from unreliable equipment to an inexperienced observer. And there’s certainly a chance that the 1913 Death Valley record could come into reassessment under the <a dir="ltr" href="https://www.ncdc.noaa.gov/extremes/ncec/," rel="noreferrer noopener">National Climate Extremes Committee </a>.

And even though our systems are much more accurate nowadays, with automated readings and no deciphering of hand-written notes, there’s still a chance that our modern systems may mess up. “You can certainly have problems at individual sites,” Erdman says, “But those are pretty rare.” Just take some of <a dir="ltr" href="https://www.baynews9.com/fl/tampa/weather/2018/10/05/weather-blog--tampa--record-highs--caused-by-sensor-error" rel="noreferrer noopener">Tampa’s 2018 record highs that ended up being inaccurate </a>due to being too closely located to toasty parking lots and highways, picking up too-high temperatures.

Just like every anomaly, there’s a chance that the old record was truly a one-in-a-million occurrence. But whether it stands or not, what really matters is that these records are being broken more and more often in a pattern, we cannot ignore—temperatures are rising worldwide, and the entire planet is now experiencing the wrath of intensified weather.

“What you’re gonna see is that there’s an upward trend,” McKinnon says. “And you can see breaking records with a greater probability.”

<a dir="ltr" href="https://www.popsci.com/authors/sara-kiley-watson/">Sara Kiley Watson </a>is an assistant editor at PopSci. Her work has also been featured in NPR and Business Insider. Contact the author <a dir="ltr" href="mailto:sarakiley@popsci.com" title="Contact to Sara Kiley Watson">here. </a>

What the 'hottest day on record' really means | Popular Science

Around 1200 A.D., the word ‘hack’ appeared in the English language, meaning to ‘cut with heavy blows in a random, irregular manner’.
It’s technological transformation happened in 1955 at M.I.T., in the minutes of a technology club meeting. It loosely meant working on a tech problem in a different, creative way which is not written in any instruction manual.

Hacked: A History

Self Improvement

A series of similar meanings of the word ‘hack’ were thrown in the air in the 70s, and confused with password cracker or network hacker.Unethical hacking, the malicious meddling with things clearly illegal was termed ‘black hat’ hacking, mostly involving stealing information or bypassing digital gates to access expensive services for free.

Same Word Different Meanings

Steven Levy’s 1984 bestseller ‘Hackers’ clearly defined white-hat(or useful and ethical) hacking, describing such people as heroes of the computer revolution.Hacking still has dark, illegal connotations among the general population and people less familiar with technology.People like Edward Snowden, Julian Assange, and the late Aaron Swartz were targeted by the Government for breaking laws that shouldn’t have been there in the first place.

Hackers Become Heroes And Villains

The word “hack” was around for hundreds of years before the first computer.

A psychologist <a data-event-click='{"element":"ExternalLink","outgoingURL":"http://www.cnn.com/2014/01/17/opinion/hacking-happiness-molecule/"}' dir="ltr" href="http://www.cnn.com/2014/01/17/opinion/hacking-happiness-molecule/" rel="nofollow noopener">wants to tell us </a>how to “hack the happiness molecule.” The Web site Lifehacker offers tips on “how to install a laundry chute,” “make a DIY rapid-fire mouse button,” and “how to stop giving a f*ck what people think.” Online marketers desperately want to “<a data-event-click='{"element":"ExternalLink","outgoingURL":"http://marketingland.com/growth-hacking-is-bull-69635"}' dir="ltr" href="http://marketingland.com/growth-hacking-is-bull-69635" rel="nofollow noopener">growth hack </a>.” The venture capitalist Paul Graham constantly talks about how tech entrepreneurs must have “hacker eyes”; his startup incubator, Y Combinator, runs an online news aggregator called Hacker News. A technology company recently recalled “<a data-event-click='{"element":"ExternalLink","outgoingURL":"http://www.nytimes.com/2014/03/03/technology/when-start-ups-dont-lock-the-doors.html?_r=0"}' dir="ltr" href="http://www.nytimes.com/2014/03/03/technology/when-start-ups-dont-lock-the-doors.html?_r=0" rel="nofollow noopener">a disastrous hack </a>,” while in recent months Target, Neiman Marcus, Richard Engel, and the University of Maryland have all been “hacked.”

Clearly, “hack” is the word of the moment; its technological connotations have proliferated in both scope and presence. As used above, and in the halls of Facebook, it derives from a verb that first appeared in English around 1200, meaning to “cut with heavy blows in an irregular or random fashion,” as the Oxford English Dictionary defines it. (Another strain of the word, referring to a person—especially a writer—who does undistinguished work, comes from “hackney,” as in a horse or car for hire.)

It was at M.I.T. that “hack” first came to mean fussing with machines. The minutes of an April, 1955, meeting of the Tech Model Railroad Club state that “Mr. Eccles requests that anyone working or hacking on the electrical system turn the power off to avoid fuse blowing.” The lexicographer Jesse Sheidlower, the president of the American Dialect Society, who has been tracking the recent iterations of “hack” and “hacker” for years, told me that the earliest examples share a relatively benign sense of “working on” a tech problem in a different, presumably more creative way than what’s outlined in an instruction manual.

In the nineteen-sixties, the term seems to have migrated from the M.I.T. context to computer enthusiasts in general, and, in time, became an essential part of their lexicon. The Jargon File, a glossary for computer programmers that was launched in 1975, <a data-event-click='{"element":"ExternalLink","outgoingURL":"http://www.catb.org/~esr/jargon/html/H/hacker.html"}' dir="ltr" href="http://www.catb.org/~esr/jargon/html/H/hacker.html" rel="nofollow noopener">lists eight definitions </a>for “hacker.” The first reads, “A person who enjoys exploring the details of programmable systems and how to stretch their capabilities, as opposed to most users, who prefer to learn only the minimum necessary.” The following six are equally approving. The eighth, and last, is “[deprecated] A malicious meddler who tries to discover sensitive information by poking around. Hence password hacker, network hacker. The correct term for this sense is <a data-event-click='{"element":"ExternalLink","outgoingURL":"http://www.catb.org/~esr/jargon/html/C/cracker.html"}' dir="ltr" href="http://www.catb.org/~esr/jargon/html/C/cracker.html" rel="nofollow noopener">cracker </a>.”

That “[deprecated]” was a way of whistling past the graveyard, a self-conscious attempt to marginalize what later came to be called “black hat” hacking (malicious meddling), as opposed to “white hat” hacking (free-spirited creation). The black-hat sense has been around since at least November, 1963, when M.I.T.’s student newspaper, The Tech , noted, “Many telephone services have been curtailed because of so-called hackers, according to Prof. Carlton Tucker, administrator of the Institute phone system. … The hackers have accomplished such things as tying up all the tie-lines between Harvard and M.I.T., or making long-distance calls by charging them to a local radar installation.” The term subsequently migrated to computers. In 1976, a book entitled “<a data-event-click='{"element":"ExternalLink","outgoingURL":"http://select.nytimes.com/gst/abstract.html?res=FA0B16FD3D5A107B93C1A8178DD85F428785F9"}' dir="ltr" href="http://select.nytimes.com/gst/abstract.html?res=FA0B16FD3D5A107B93C1A8178DD85F428785F9" rel="nofollow noopener">Crime by Computer </a>” included a chapter called “Trojan Horses, Time Bombs, Round Down, and the System Hacker.”

The black-hat sense proved irresistible to members of the media and other non-techies, no doubt in part because “hack” sounds malicious—not to mention that “hack” rhymes with “attack.” Steven Levy’s 1984 history of below-the-radar programmers and innovators, “Hackers,” was very much in agreement with the white-hat notion—its subtitle was “Heroes of the Computer Revolution”—but the book was so popular that it served as a sort of Trojan horse for the opposition. As Levy wrote in an afterword to a 1993 edition:

… the popularization of the term was a disaster. Why? The word “hacker” had acquired a specific and negative connotation. The trouble began with some well-publicized arrests of teenagers who electronically ventured into forbidden digital grounds, like government computer systems. It was understandable that the journalists covering these stories would refer to the young perps as hackers. After all, that’s what the kids called themselves . But the word quickly became synonymous with “digital trespasser.”

To give an indication of what Levy means, here are the first three uses of the word in the Times in 1990:

Computer hackers often sell the stolen codes to other students for a few dollars.

Mr. Poulsen, who is charged with the most crimes, has a history as a “hacker,” who began trespassing in university and government computers as a teen-ager using the assumed name Dark Dante, according to a profile in California magazine in 1984.

Mr. Morris, viewed by some as a dedicated computer researcher, by others as a reckless hacker, testified that it was never his intention to slow down computers or damage Internet data.

Although Lifehacker and other neutral or positive applications of the word are increasingly prominent, the black-hat meaning still prevails among the general public. Indeed, it has probably influenced the interpretation and enforcement of the Computer Fraud and Abuse Act. It’s as if the mere existence of the term “hacker” has added ammunition to the prosecution of such figures as Edward Snowden, Julian Assange, Chelsea Manning, and <a dir="ltr" href="http://www.newyorker.com/reporting/2013/03/11/130311fa_fact_macfarquhar">Aaron Swartz, the Internet activist </a>who was indicted and charged with eleven violations of the act in 2011. His alleged offense was downloading many academic articles from a proprietary database; the scene of the crime, perhaps fittingly, was M.I.T.

Even as the mainstream usage of “hacker” took on its darker connotation, the geeks continued using it to mean what it always had: a righteous dude. As linguist Geoff Nunberg pointed out in a recent <a data-event-click='{"element":"ExternalLink","outgoingURL":"http://www.npr.org/blogs/alltechconsidered/2014/01/16/263088398/hackers-techies-what-to-call-san-franciscos-newcomers"}' dir="ltr" href="http://www.npr.org/blogs/alltechconsidered/2014/01/16/263088398/hackers-techies-what-to-call-san-franciscos-newcomers" rel="nofollow noopener">“Fresh Air” </a>commentary, “Within tech culture, ‘hacker’ has become a shibboleth that identifies one as a member of the tribe.” When an M.I.T. student died in a plane crash in 1993, one of his fraternity brothers <a data-event-click='{"element":"ExternalLink","outgoingURL":"http://tech.mit.edu/V113/N60/crash.60n.html"}' dir="ltr" href="http://tech.mit.edu/V113/N60/crash.60n.html" rel="nofollow noopener">eulogized him by saying </a>, “He was a hacker in every sense of the word, and we’re all going to miss him greatly.”

<a data-event-click='{"element":"ExternalLink","outgoingURL":"http://www.benyagoda.com/"}' dir="ltr" href="http://www.benyagoda.com/" rel="nofollow noopener">Ben Yagoda </a>teaches journalism at the University of Delaware and is the author, most recently, of “How to Not Write Bad: The Most Common Writing Problems and the Best Ways to Avoid Them.”

Illustration by Jordan Awan.

A Short History of “Hack”

As more and more interaction goes online due to work being increasingly remote, we find that we are staring at our digital selves on the laptop or smartphone screen more often than usual. Social scientists are looking at the long-term effects of being connected via screens in our homes, isolated from real people.
If we like ourselves, we would find pleasure in being on video calls, but if we are self-critical, the same negative feelings would be amplified. The screens act like digital mirrors, showing us more of what we believe in.

Digital Mirrors

Being self-concerned while on a video call is natural. We can see after a while that our face is tensed up and has a quizzical look. 
New studies show that friends behave differently in video interactions and the in-person ones. Virtual meetings put us in a muted state, both physically and emotionally.

Virtual Vs Real Communication

A small percentage of people are excessively focused on real or imagined flaws related to their looks, and look in the mirror quite often. The people find mirrors a force that controls, imprisons and paralyses them.
Even if we don’t fall under that bracket, constantly seeing ourselves in the (digital) mirror may increase the self-analysis, monitoring or evaluation.

Always Looking In A Mirror

Large group video calls often tend to be comparison contests, increasing self-critical behaviour.
To minimize negative feelings or bad habits, we can fiddle with the settings to minimize our faces, or put the screen image placement to the bottom of the screen. We can also use sticky notes to block any distractions and focus on actual work. We can also put our complete focus on the person we are interacting with, looking for visual cues.

Minimizing Virtual Comparisons And Distractions

We’re on video chat all day long. Here’s what it’s doing to our brains.

We’re on video chat all day long. Here’s what it’s doing to our brains.

The other day, my social schedule was packed. At 10 a.m., I had a Google Hangout meeting with my editor. At noon, I met some childhood friends on Zoom for a virtual lunch date. At 3 p.m., I called my parents on FaceTime so they could see my 4-month-old son. At 5 p.m., I cracked a beer during virtual happy hour with a friend who lives a mile away. And at 7 p.m., when my husband was leaving his job at the local hospital, I FaceTimed him so he could say goodnight to the baby.

After all that talking, I crawled into bed feeling mentally exhausted, even though I hadn’t seen anyone besides my son in person. I’d spent over four hours on video calls; that’s 240 minutes spent looking at other people on camera — and looking at my own face on the screen. My face hurt from smiling. Was I enjoying people’s company that much more, or — crap — was I just trying to look more presentable and interested because I could see my own reactions on the screen? And was everyone else experiencing this same, odd phenomenon of fixating on their own faces while video chatting, too?

Social distancing measures to combat the spread of the novel coronavirus have made <a dir="ltr" href="https://www.axios.com/video-chat-apps-coronavirus-f312eaa3-2fac-476f-af73-6ea00b448370.html">video chatting </a>more essential than ever before. For many of us, it’s the only form of social support we have. Experts say we should take advantage of it.

“I think is a valuable resource,” says Paul Gebben, a psychotherapist from the Seattle area who specializes in telemedicine. “I can see somebody’s eyebrow go up. I can see people’s reactions to things. I don’t see any of that in a phone call! It’s all about the non-verbals.”

Seeing my straight-out-of-the-shower hair and my makeup-less face on the screen stresses me out.

But if we have to spend the next few months in social isolation, only connecting via screens, what will that do to us psychologically? Will we become more conceited? More apt to perform? More self-critical? Social scientists are just starting to dive into those questions, but according to experts, seeing ourselves in the corner of a screen is a lot like looking in a “digital mirror.” If you like yourself, you’ll probably feel even more positive if you see your face on the screen every day. But if you’re self-critical, that tendency will come out, too, especially during this particularly odd and difficult time.

Every afternoon, my son FaceTimes with his grandparents. They’ve had to miss things like his first laugh and his newly-garbled babbles, so these sessions are important for building relationships and keeping everyone up-to-date. And compared with other forms of screen time, it’s relatively benign. Several <a dir="ltr" href="https://www.sciencedaily.com/releases/2016/07/160715115023.htm">studies </a>show that for kids, video chatting doesn’t seem to have the same negative effects as using other online tools. For kids and adults, responsive conversations aren’t linked to the negative outcomes of mindlessly scrolling through Instagram, Twitter, and Facebook (which can cause <a dir="ltr" href="https://psycnet.apa.org/record/2018-15210-001">increased anxiety </a>and worsened sleep).

But lately, I find myself turning the camera more and more in the direction of my son. Seeing my straight-out-of-the-shower hair and my makeup-less face on the screen stresses me out. I’m letting people visually into my home, a place where I’m not usually concerned about how I look. The result, for me at least, seems to be self-criticism.

Gebben has experienced this as well. “When I see people in those Brady Bunch tiles, I am checking my own face,” he says. “I’m like, ‘you’ve had that quizzical look on your face a while. Relax your face.’ Whether it’s a small group chat or with family, I consider how I’m coming across.”

There’s research behind this editing behavior: In a<a dir="ltr" href="https://cyberpsychology.eu/article/view/4285/3330">2013 study </a>published in the Journal of Psychosocial Research on Cyberspace , researchers found that video chats promoted bonding between friends, much like in-person interactions. But there was one big difference between the two: The friendship-oriented behaviors that happen automatically in-person didn’t happen at all over video. Researchers call these “nonconscious, automatic affiliation cues,” and their findings suggest that we’re all a bit more muted, emotionally and physically, when we communicate through a screen.

There may also be an element of distraction in getting more familiar with a new mode of conversation (and our own personal hang-ups). Gebben notes that we’re not used to encountering our own images this frequently; while it’s bizarre, it could start to feel more normal as time passes.

And while psychological studies have yet to delve into this specific, self-reflective element of video chatting, researchers have spent time <a dir="ltr" href="https://journals.sagepub.com/doi/abs/10.1177/1359105315581516?journalCode=hpqa&amp;">studying </a>what happens when you look in a mirror for a long period of time. And that depends largely on your initial perceptions of your body. People who have body dysmorphic disorder, a psychiatric diagnosis that affects between 1.7 and 2.9 percent of the general population and involves being excessively preoccupied with real or imagined defects and flaws, are more likely to look in the mirror and think negatively about themselves. These people described mirrors as “controlling, imprisoning, and disempowering forces” that had a “paralyzing effect” on their lives. For them, and for others who struggle with psychiatric conditions, video chatting may feel traumatizing.

Even if you don’t struggle with these disorders, video chats can still trigger a less-intense — but still-noticeable — stress response. Whatever you’re dealing with emotionally could intensify when you’re faced with your own image on camera. “If you have anxiety, or you’re very self-critical, you’ll likely feel those symptoms activated,” says Dana Rose Garfin, a faculty member at the Sue &amp; Bill Gross School of Nursing.

Plus, noticing our pathological tendencies from an outside perspective, which happens when you see yourself more often, can actually exacerbate them. When I asked Gebben about my people-pleasing tendencies to smile excessively and nod enthusiastically during video chats, he suggested that my instincts might be heightened by seeing myself.

“From an evolutionary perspective, we want to put our best foot forward to be part of the group,” says Garfin. “It’s natural for us to look at ourselves [on screen] as a form of self-monitoring.”

I was familiar with this feeling before the lockdown. At my first job, our all-staff calls took place on Zoom — sometimes with more than 100 people in attendance. As I scrolled through people’s images on the grid, I remember thinking: He has a better desk setup. Her lighting is so great! Look at her husband working in the background . If someone else looked extremely put-together, I’d fiddle with my hair for the rest of the video call, to make sure I looked as professional as possible.

This social comparison behavior happens on other online platforms, too; it’s why you might feel elated when you scroll Instagram and realize that some aspect of your life is better than someone else’s, but why you end up feeling like crap after a long session of scrolling through a fitness influencer’s perfectly crafted photos. Large-group video chats likely ignite this same self-critical, comparative behavior.

So what can you do if staring at yourself on a video screen can prompt negative feelings and bad habits? Gebben suggests fiddling with your on-screen setup as a good place to start. If there’s a way to minimize your own face, it might be worth doing so. In the HIPAA-compliant telemedicine program he uses for his sessions, his image appears in the bottom corner of the screen, rather than the top or in a grid. That position that may make it easier to ignore.

He also uses sticky notes to block out distractions in his clients’ backgrounds, so he can focus on connecting — a good way, perhaps, to avoid spiraling over a colleague’s perfectly-appointed bookcase.

Also, since there’s that added element of distraction in video chats, it’s worth taking extra care to maintain that focus on your conversation partner, as you would during an in-person interaction. What are they wearing? How are they feeling? What emotions do you see etched across their face?

“People feel good when they’re trying to help other people,” Garfin says. “It’s helpful to reach out to others to give support and receive it. That can give more meaning to the situation, too.”

She suggests asking open-ended questions about how your conversation partner is faring during quarantine, or how their day was. In a group chat setting, attempt to draw out the quieter members by saying their names or directing questions at them. When you connect, really try to connect in the absence of physical touch.

For added peace of mind, applications like Zoom also offer tools to help you adjust what you see of yourself. Zoom’s <a dir="ltr" href="https://www.elitedaily.com/p/heres-how-to-get-zooms-touch-up-feature-to-give-yourself-airbrushed-look-22630742">“touch up my image” </a>feature applies a light filter to your face, and you can now add your own background if you want to block out that pile of laundry behind you. <a dir="ltr" href="https://www.theverge.com/2020/4/8/21202907/zoom-tips-video-call-lighting-audio-look-your-best">Columns </a>about how to improve the lighting and audio of your video chat also abound.

For my part, I now attempt to hide my image in the bottom corner of the screen as often as possible; during a virtual therapy session last week, I even covered the image of my face on the screen with a sticky note. During large-group Zoom calls, I switch to speaker view so I can focus on the person who’s talking instead of my own bad hair day.

Some <a dir="ltr" href="https://www.sciencedirect.com/science/article/abs/pii/S1740144519300130">research </a>backs up the benefits of positive self-talk, so I’ve been working on self-compassion, too, mentally saying nice things when I see myself — a bit disheveled but still functioning fairly well — on that video chat screen. This is how I always looked, anyway. And maybe quarantine is the perfect time to embrace that unedited image.

Published on <time datetime="2020-04-22T08:13:47-04:00" dir="ltr">April 22, 2020<time dir="ltr"> </time> </time>

<a dir="ltr" href="https://twitter.com/jenni_gritters">Jenni Gritters </a> is a writer based in Seattle.

Illustration by Angela Pyne/images via iStock

I can’t stop staring at my own face on Zoom - Experience Magazine

From a young age, we learn how to be a good friend to others. We learn how to share and to treat others how we want to be treated. 
Yet, many of us don&#39;t receive guidance on how to treat ourselves with kindness. We might even believe that being kind towards ourselves is self-indulgent or weak.

Befriending yourself

Self-compassion involves treating yourself with the same kindness with which you&#39;d treat a loved one. Self-compassion consists of three ingredients:
<ul>
<li>Self-kindness: Offering warmth and understanding to yourself.</li>
<li>Common humanity: Acknowledging that we all make mistakes and experience pain.</li>
<li>Mindfulness: Observing your thoughts without becoming consumed by them.</li>
</ul>

Three ingredients of self-compassion

Researchers found that self-compassion helps people take personal responsibility for problems and help them persist when facing obstacles. 
If we are self-compassionate, we create a safe space to look at our embarrassing missteps. We can recognise that failures are natural. Without self-criticism and shame, it&#39;s easier for self-compassionate people to improve and move forward.

Self-compassion is a healthy response to suffering

You can either fill your tank with criticism or with compassion. Both will get you moving, but self-compassion will last longer and cause less damage over time.
When you practice being kind to yourself, you will find it easier to get up if you failed at something, apologise after losing your cool, or return to exercising after neglecting it.

Your words of self-talk are your fuel

It is not an elusive trait reserved for a few lucky ones. We can train our self-compassion, for example, through writing exercises (writing a letter to yourself from the perspective of a caring friend), imagery, or meditations. These exercises can help us respond to ourselves with encouragement and care.
Yet, most people find cultivating self-compassion very difficult. Research found that just changing participants beliefs about the usefulness of self-compassion helped them cope better.

We can all cultivate compassion

<ul>
<li>Notice what you believe about self-compassion. What do you think would happen if you were self-compassionate? What would happen if you let go of harsh self-criticism?</li>
<li>Notice how you talk to yourself. Is your self-talk negative? Do you hold yourself to impossible standards?</li>
<li>Examine your assumptions about self-compassion.</li>
</ul>
At first, self-compassion might feel odd, scary or difficult. Be patient with yourself. Getting better at self-compassion takes practice.

Correcting our assumptions about self-compassion

Contrary to popular belief, it’s not self-indulgent to practise self-compassion. In fact, it helps you to care for others

Photo by Carolyn Drake/Magnum

I’ll never forget the time I overheard one of my high-school classmates repeatedly calling herself stupid in front of the bathroom mirror. When I recognised her voice, chills ran down my spine. I’d always thought of her as one of the kindest people in the whole school. I was shocked to hear how cruel she was to herself when she thought she was on her own.

From a young age, we learn how to be a good friend to others. In kindergarten or nursery school, we’re taught how to share, cooperate and play. Any child who calls other kids dumb, losers or ‘fart face’ is swiftly scolded or given a time out. All in all, we grow up learning to follow the golden rule: ‘Treat others how you want to be treated.’

Yet many of us receive no guidance on how to be a friend to ourselves. In fact, we might even get counterproductive messaging about what it means to treat ourselves with kindness. We might come to believe that being kind towards ourselves is self-indulgent, lazy or weak.

As a clinical psychologist in training, I’ve discovered such self-beratement is commonplace. For example, people often judge their bodies, work performance or parenting abilities by standards to which they’d never hold others. Many people call themselves names they’d never dare utter to friends or family members, or even to people they dislike.

It’s little surprise that the psychological concept of ‘self-compassion’ is cloaked in controversy. At its core, self-compassion involves treating yourself with the same kindness and consideration with which you’d treat a loved one. Just as compassion begins by recognising another’s pain, self-compassion begins by recognising when you, yourself, are suffering. A self-compassionate response, <a dir="ltr" href="https://www.tandfonline.com/doi/abs/10.1080/15298860309027" rel="nofollow noreferrer noopener">according </a>to a leading self-compassion researcher, Kirstin Neff at the University of Texas, entails three critical ingredients:

<ol><li>self-kindness: offering yourself warmth and understanding rather than self-judgment; </li><li>common humanity: remembering that all human beings make mistakes and experience pain, rather than feeling isolated in your suffering; and </li><li>mindfulness: observing your thoughts and emotions in a balanced way, without becoming consumed by them. </li> </ol>

I’ve found that the idea of self-compassion elicits reactions ranging from an enthusiastic ‘Sign me up!’ to suspicion or even <a dir="ltr" href="https://bpspsychub.onlinelibrary.wiley.com/doi/abs/10.1348/147608310X526511" rel="nofollow noreferrer noopener">fear </a>. Upon the mere mention of self-compassion, a host of thoughts can bubble up: ‘Self-compassion is just not for me.’ ‘Aren’t people too soft on themselves these days?’ ‘I need self-criticism to motivate me to achieve my goals.’ Or, ‘If I’m self-compassionate, won’t I just sit on the couch and eat Ben and Jerry’s all day?’

Without the heavy baggage of self-criticism and shame, it’s easier for self-compassionate people to grow, improve and move forward

These beliefs have consequences, including affecting how people respond to life’s challenges. For instance, in one <a dir="ltr" href="https://journals.sagepub.com/doi/abs/10.1177/0146167220965303?journalCode=pspc" rel="nofollow noreferrer noopener">study </a>, my colleagues Patricia Chen, Jamil Zaki and I looked into the coping strategies used by people who were disappointed and upset following the outcome of the 2016 US presidential election. Those who viewed self-compassion positively were more likely than others to draw upon self-compassion in a beneficial way to help them get through the difficult times – for instance, they reported using more active strategies to manage their emotions, such as seeking support from others, and relied less upon unhelpful strategies, such as distraction or self-blame. This not only helped them feel better, it worked better too – our participants who practised more self-compassion reported having more intentions to improve themselves and the situation, such as by committing to become more politically active.

Our work echoes what research finds time and time again – self-compassion is a healthy response to suffering. It is critical not only to our <a dir="ltr" href="https://iaap-journals.onlinelibrary.wiley.com/doi/abs/10.1111/aphw.12051" rel="nofollow noreferrer noopener">wellbeing </a>but also helps us rise to challenges. For example, other researchers have found that self-compassion helps people take personal <a dir="ltr" href="https://journals.sagepub.com/doi/abs/10.1177/0146167212445599" rel="nofollow noreferrer noopener">responsibility </a>for transgressions and <a dir="ltr" href="https://www.tandfonline.com/doi/abs/10.1080/13576500444000317" rel="nofollow noreferrer noopener">persist </a>following obstacles, such as a disappointing test grade. Contrary to assumptions that self-compassion is selfish, self-compassion even helps us to be kinder towards <a dir="ltr" href="https://www.tandfonline.com/doi/abs/10.1080/17439760.2013.831465" rel="nofollow noreferrer noopener">others </a>. All of this might sound counterintuitive: how can something as unassuming as self-compassion help us become better, more resilient versions of ourselves?

An interesting thing happens when we’re self-compassionate – it becomes safe for us to admit our missteps to ourselves. Think about it this way: would you rather share an embarrassing mistake with someone with a track record of responding kindly – or with someone who might fly off the handle with harsh criticism?

In this way, when mistakes or perceived failures arise, self-compassionate people are able to recognise them for what they are: normal human happenings. Then, without the heavy baggage of self-criticism and shame, it’s easier for self-compassionate people to grow, improve and move forward bravely.

In her popular TEDx <a dir="ltr" href="https://www.youtube.com/watch?v=IvtZBUSplr4" rel="nofollow noreferrer noopener">talk </a>from 2013, Neff offered a helpful analogy for understanding why self-compassion works so well. Imagine that a child returned home from school upset, having received a failing grade in mathematics. A parent could respond with harsh criticism, expressing disappointment, anger or even shame. They could yell and question the intellect of the child. For a short while, the child might study harder. But over time, the child could become depressed and quit mathematics altogether, as the consequences of failing again are too high. Alternatively, a parent could respond to the child with compassion, recognising and validating the child’s feelings of disappointment (eg, ‘I can tell how upset you are. That sounds really tough’), reminding them that everyone struggles occasionally, and helping them maintain a balanced perspective (eg, ‘There are still more quizzes ahead of you. Let’s figure out together how we can help you feel prepared and ready for the next one’).

Notice that the compassionate response didn’t involve turning a blind eye to the test grade. Nor did it entail stroking the child’s ego. Instead, it involved creating a safe and nurturing environment, where mistakes are OK for the child to confront.

Put another way, your words of self-talk are the fuel: you can choose to fill your tank with either criticism or compassion. Both will get you moving, but the self-compassionate variety lasts longer and causes less harm to the engine in the end. When you’re kind towards yourself, you’ll find it easier to confront life’s many challenges, whether that be studying after receiving a failing test grade, apologising to someone after losing your cool, or returning to the gym even when you feel weak. Importantly, self-compassion enables us to confront these hurdles head-on, without becoming consumed by feelings of inadequacy.

Self-compassion is not an elusive trait that only some people can possess. There are concrete ways for us all to cultivate compassion, both for others and for ourselves. Researchers have created programmes (eg, the Mindful Self-Compassion <a dir="ltr" href="https://chrisgermer.com/mindful-self-compassion-msctm/" rel="nofollow noreferrer noopener">programme </a>), <a dir="ltr" href="https://self-compassion.org/mindful-self-compassion-workbook/" rel="nofollow noreferrer noopener">workbooks </a>and <a dir="ltr" href="https://self-compassion.org/category/exercises/" rel="nofollow noreferrer noopener">resources </a>to help people build greater self-compassion. We can train our self-compassion muscle in various ways, for example, through <a dir="ltr" href="https://psyche.co/guides/to-start-to-heal-from-trauma-in-your-life-write-about-it" rel="noopener">writing </a>exercises (eg, writing a letter to oneself from the perspective of an unconditionally caring friend), imagery or meditations. These exercises train us to respond to our own pain or perceived inadequacies just like we’d respond to those of a friend – with encouragement and caring.

Self-compassion is about relating to yourself in a more constructive, nurturing way. It’s not about feeling good all the time

And yet, if you’re like most people, getting to the self-compassion gym is the hardest part. If you have doubts that the gym will bring any benefits, you’re unlikely to visit! Encouragingly, in our <a dir="ltr" href="https://journals.sagepub.com/doi/abs/10.1177/0146167220965303?journalCode=pspc" rel="nofollow noreferrer noopener">work </a>, we found that just changing participants’ beliefs about the usefulness of self-compassion helped them cope better with challenges. When we told people that the research shows that self-compassion actually improves motivation rather than harming it, they were subsequently more likely to practise self-compassion during difficulties. This, in turn, helped them to cope better and seek self-improvement.

Our work thus underscores the importance of taking the time to understand and gently correct your <a dir="ltr" href="https://self-compassion.org/what-self-compassion-is-not-2/" rel="nofollow noreferrer noopener">assumptions </a>about self-compassion. Doing so could help you respond more effectively to the inevitable bumps in the road ahead.

First, notice what beliefs you have about self-compassion . Ask yourself: what have other people told you, either through words or actions, about self-compassion? Did parental figures in your life practise compassion? If so, did they include themselves within their sphere of compassion? What do you believe would happen if you were self-compassionate? What do you think would happen if you let go of harsh self-criticism?

Next, notice how you talk to yourself . If you’re like most people, your mind is filled with a steady stream of chatter and yet, just like when you mindlessly consume popcorn during a movie without noticing its texture or flavour, you might not pause to reflect on your self-talk. Does it tend to be <a dir="ltr" href="https://psyche.co/guides/how-to-get-over-never-good-enough-a-practical-guide" rel="noopener">negative </a>? Do you hold yourself to impossible standards? You’ll be spending the rest of your life with this voice, so take the time to truly get to know it and consider making conscious adjustments if necessary.

Finally, check your assumptions about self-compassion . Remember that, time and time again, researchers find that self-compassion not only helps us feel better but has positive practical consequences too. Self-compassion is a powerful motivational tool that can help you persist, even in the face of challenges.

At first, self-compassion might feel foreign, scary or difficult. Be patient with yourself. Remember that self-compassion is about relating to yourself in a more constructive and nurturing way, and that it might take time to develop. It’s not about feeling good all the time. I’ve seen how, just like beginning a new physical workout regimen, the journey to relate to yourself with compassion can be difficult, even painful at the start.

For many people, self-compassion is a radically different approach than they’re used to – it means having compassion for yourself that’s unconditional, regardless of your circumstances or achievements. This stands at odds with a culture that often rewards us for accomplishments, capital and accolades. Where the ego whispers a siren’s call (achieve more, do better, and you will be worthy ), self-compassion is the reliable friend that we all deserve (I believe in you, I’m here for you, no matter what).

Thinking back to my high-school classmate berating herself in front of the bathroom mirror, I wish she could have known that she didn’t have to be her own bully. If she’d believed in the power of self-compassion, I might have instead overheard a self-compassionate pep talk: ‘Receiving that bad test score really hurt, but it doesn’t say anything bad about me as a person. I know that other people in class are struggling, too, and that I’m not alone in this. I’ll ask for help on how to study more effectively, and get the support I need and deserve.’ In my clinical work and research, I’ve seen that self-compassion is a resiliency supercharger. If my classmate could have befriended herself, I bet she’d have found school would improve, and her life down the road would have grown much richer.

Know that this applies to you, too. While the journey towards cultivating greater self-compassion might seem daunting, it’s worthwhile. With you by your own side, you will be unstoppable.

Self-compassion is not self-indulgence: here’s how to try it | Psyche Ideas

Planes can fly quite easily without engines, as gliders (planes without engines), paper planes, and gliding birds show us.
A plane&#39;s engine is designed to move the plane forward at high speed. The wings move a plane upward. At high speed, the air flows fast over the wings and throws the air down toward the ground, generating an upward force, or lift. The upward force overcomes the plane&#39;s weight and keeps it in the sky.

How planes fly

Sciency

Wings make lift by changing the direction and pressure of the air that the plane comes into contact with as the engines push the planes through the sky.

Airplanes: How wings make lift

Most aeroplane wings are curved on the upper surface and flatter on the lower surface, making a sectional shape, named an airfoil. 
<ul>
<li>As a curved airfoil wing flies through the sky, it deflects the air and changes the air pressure above and below it.</li>
<li>The air pressure changes because the air that flows over the curved upper surface wants to move in a straight line, but the curve pulls the air around and back down, causing the air to stretch out into a bigger volume, lowering the pressure.</li>
<li>The pressure of the air under the wing increases for the opposite reason.</li>
<li>The difference in air pressure between the upper and lower surfaces causes a difference in air speed. When they arrive at the tail end of the wing, the molecules of both will be speeding downward, producing lift.</li>
</ul>

Airplanes: Explaining pressure differences

The second aspect of making lift: 
<ul>
<li>According to Isaac Newton&#39;s third law of motion, if air gives an upward force to a plane, the plane must provide an equal and opposite downward force to the air. That means that the plane generates lift by using its wings to push air downward behind it.</li>
<li>The wings are tilted back very slightly, so they hit the air at an angle of attack. The angled wings push down the varied airflow from above and below the wing to create lift.</li>
</ul>
The pressure difference that a wing creates and the downwash of the air behind it generate the same effect: The angled airfoil wing creates a pressure difference that causes a downwash and produces lift.

Downwash (downward moving draft)

Air that flows at a certain angle (generally 15 deg) over the top and bottom of a wing follows the curve of the wing surfaces very closely. But as the angle increases (the angle of attack), the smooth airflow behind the wing becomes more turbulent and reduces the lift.
<ul>
<li>Planes can fly without airfoil-shaped wings. What is crucial for a plane is the angle of attack.</li>
<li>The bigger the wings, the more lift they create. </li>
<li>But small wings can also generate a great deal of lift if they move fast enough. Extra lift at takeoff is produced with flaps on the wings to push more air down.</li>
<li>Lift and drag vary with the square of your speed: If the place goes twice as fast relative to the oncoming air, its wings produce four times as much lift and drag.</li>
</ul>

Airplanes: How much lift you can make

A plane throws the air down behind it by making a spinning vortex - a kind of mini-tornado.
Most of the vortex is moving downward, but not all. There&#39;s a huge draft of air moving down in the center, but the air also swirls upward on either side of the wingtips, reducing lift.

Wing vortices

When you change something&#39;s direction of travel, you change its velocity - the speed it has in a particular direction. A change in direction always means a change in velocity and acceleration.
Newton&#39;s laws of motion state that you can only change the speed of something or change its direction of travel by applying a force to it.

How planes steer

Another way to look at steering is to think of it as stopping something from going in a straight line and going in a circle. That means you have to give it a centripetal force.
Things that move in a circle always have something acting on them to give them a centripetal force. For example, if you&#39;re on a skateboard, you can tilt the deck and lean over, so your weight helps to provide centripetal force.

Airplanes: The centripetal force

If you&#39;re in a plane and steering around a circle, the centripetal force comes from leaning into a curve, just like a cyclist leans into a bend.
Steering involves banking, where the plane tilts to one side causing the one wing to dip. The plane&#39;s overall lift is tilted at an angle, making some of the lift act sideways. This sideways part of the lift provides the centripetal force that makes the plane go around in a circle. But turning the plane in a circle will make it lose lift and altitude, unless the pilot uses the elevators to increase the angle of attack to cause lift again.

Airplanes: Steering in theory

You steer something flying through the air at high speed by making the air flow in a different way past the wings.
Planes are moved up and down, steered from side to side, and made to stop by a complex collection of moving flaps called control surfaces on the leading and trailing edges of the wings and tail. They are called ailerons, elevators, rudders, spoilers, and air brakes.

Airplanes: Steering in practice

<ul>
<li>Build a basic paper plane that flies in a straight line.</li>
<li>Cut or rip the back of the wings to make some ailerons.</li>
<li>Tilt them up and down and see what effect they have in different positions.</li>
<li>Tilt one wing up and the other down and see what difference that makes.</li>
<li>Try making a new plane with one wing bigger than the other, or heavier by adding paperclips.</li>
<li>A paper plane can be steered by making one wing generate more lift than the other.</li>
</ul>

Experiment to understand control surfaces

<ul>
<li>Fuel tanks: The fuel is safely packed inside the plane&#39;s enormous wings.</li>
<li>Landing gear: Planes take off and land on wheels. The wheels are retracted into the undercarriage by hydraulic rams to reduce drag when the plane is in the sky.</li>
<li>Radio, radar and satellite systems are essential for navigation.</li>
<li>Pressurized cabins: Air pressure falls with height above the Earth&#39;s surface. Planes have pressurized cabins with heated air steadily pumped so people can breathe adequately.</li>
</ul>

Key parts of planes

An easy-to-understand explanation of how planes get up into the air and stay there.

If you've ever watched a jet plane taking off or coming in to land, the first thing you'll have noticed is the noise of the engines. <a dir="ltr" href="https://www.explainthatstuff.com/jetengine.html">Jet engines </a>, which are long metal tubes burning a continuous rush of fuel and air, are far noisier (and far more powerful) than traditional <a dir="ltr" href="https://www.explainthatstuff.com/how-propellers-work.html">propeller </a>engines. You might think engines are the key to making a plane fly, but you'd be wrong. Things can fly quite happily without engines, as gliders (planes with no engines), paper planes, and indeed gliding birds readily show us.

Photo: Four forces act on a plane in flight. When the plane flies horizontally at a steady speed, lift from the wings exactly balances the plane's weight and the thrust exactly balances the drag. However, during takeoff, or when the plane is attempting to climb in the sky (as shown here), the thrust from the engines pushing the plane forward exceeds the drag (air resistance) pulling it back. This creates a lift force, greater than the plane's weight, which powers the plane higher into the sky. Photo by Nathanael Callon courtesy of US Air Force.

If you're trying to understand how planes fly, you need to be clear about the difference between the engines and the wings and the different jobs they do. A plane's engines are designed to move it forward at high speed. That makes air flow rapidly over the wings, which throw the air down toward the ground, generating an upward force called lift that overcomes the plane's weight and holds it in the sky. So it's the engines that move a plane forward , while the wings move it upward .

Photo: Newton's third <a dir="ltr" href="https://www.explainthatstuff.com/motion.html">law of motion </a>explains how the engines and wings work together to make a plane move through the sky. The force of the hot exhaust gas shooting backward from the jet engine pushes the plane forward. That creates a moving current of air over the wings. The wings force the air downward and that pushes the plane upward. Photo by Samuel Rogers (with added annotations by explainthatstuff.com) courtesy of US Air Force. Read more about how engines work in our detailed article on <a dir="ltr" href="https://www.explainthatstuff.com/jetengine.html">jet engines </a>.

In one sentence, wings make lift by changing the direction and pressure of the air that crashes into them as the engines shoot them through the sky.

Okay, so the wings are the key to making something fly—but how do they work? Most airplane wings have a curved upper surface and a flatter lower surface, making a cross-sectional shape called an airfoil (or aerofoil, if you're British):

Photo: An airfoil wing typically has a curved upper surface and a flat lower surface. This is the wing on NASA's solar-powered Centurion plane. Photo by Tom Tschida courtesy of <a dir="ltr" href="http://www.nasa.gov/centers/armstrong/home/index.html" rel="noopener">NASA Armstrong Flight Research Center </a>.

In a lot of science books and web pages, you'll read an incorrect explanation of how an airfoil like this generates lift. It goes like this: When air rushes over the curved upper wing surface, it has to travel further than the air that passes underneath, so it has to go faster (to cover more distance in the same time). According to a principle of aerodynamics called Bernoulli's law, fast-moving air is at lower pressure than slow-moving air, so the pressure above the wing is lower than the pressure below, and this creates the lift that powers the plane upward.

Although this explanation of how wings work is widely repeated, it's wrong: it gives the right answer, but for completely the wrong reasons! Think about it for a moment and you'll see that if it were true, acrobatic planes couldn't fly upside down. Flipping a plane over would produce "downlift" and send it crashing to the ground. Not only that, but it's perfectly possible to design planes with airfoils that are symmetrical (looking straight down the wing) and they still produce lift. For example, paper airplanes (and ones made from thin balsa wood) generate lift even though they have flat wings.

"The popular explanation of lift is common, quick, sounds logical and gives the correct answer, yet also introduces misconceptions, uses a nonsensical physical argument and misleadingly invokes Bernoulli's equation."

Professor Holger Babinsky, Cambridge University

But the standard explanation of lift is problematic for another important reason as well: the air shooting over the wing doesn't have to stay in step with the air going underneath it, and nothing says it has to travel a bigger distance in the same time. Imagine two air molecules arriving at the front of the wing and separating, so one shoots up over the top and the other whistles straight under the bottom. There's no reason why those two molecules have to arrive at exactly the same time at the back end of the wing: they could meet up with other air molecules instead. This flaw in the standard explanation of an airfoil goes by the technical name of the "equal transit theory." That's just a fancy name for the (incorrect) idea that the air stream splits apart at the front of the airfoil and meets up neatly again at the back.

How airfoil wings generate lift#1: An airfoil splits apart the incoming air, lowers the pressure of the upper air stream, and accelerates both air streams downward. As the air accelerates downward, the wing (and the plane) move upward. The more an airfoil diverts the path of the oncoming air, the more lift it generates.

So what's the real explanation? As a curved airfoil wing flies through the sky, it deflects air and alters the air pressure above and below it. That's intuitively obvious. Think how it feels when you slowly walk through a swimming pool and feel the force of the water pushing against your body: your body is diverting the flow of water as it pushes through it, and an airfoil wing does the same thing (much more dramatically—because that's what it's designed to do). As a plane flies forward, the curved upper part of the wing lowers the air pressure directly above it, so it moves upward.

Why does this happen? As air flows over the curved upper surface, its natural inclination is to move in a straight line, but the curve of the wing pulls it around and back down. For this reason, the air is effectively stretched out into a bigger volume—the same number of air molecules forced to occupy more space—and this is what lowers its pressure. For exactly the opposite reason, the pressure of the air under the wing increases: the advancing wing squashes the air molecules in front of it into a smaller space. The difference in air pressure between the upper and lower surfaces causes a big difference in air speed (not the other way around, as in the traditional theory of a wing). The difference in speed (observed in actual wind tunnel experiments) is much bigger than you'd predict from the simple (equal transit) theory. So if our two air molecules separate at the front, the one going over the top arrives at the tail end of the wing much faster than the one going under the bottom. No matter when they arrive, both of those molecules will be speeding downward —and this helps to produce lift in a second important way.

If you've ever stood near a <a dir="ltr" href="https://www.explainthatstuff.com/helicopter.html">helicopter </a>, you'll know exactly how it stays in the sky: it creates a huge "downwash" (downward moving draft) of air that balances its weight. Helicopter rotors are very similar to airplane airfoils, but spin around in a circle instead of moving forward in a straight line, like the ones on a plane. Even so, airplanes create downwash in exactly the same way as helicopters—it's just that we don't notice. The downwash isn't so obvious, but it's just as important as it is with a chopper.

This second aspect of making lift is a lot easier to understand than pressure differences, at least for a physicist: according to Isaac Newton's third law of <a dir="ltr" href="https://www.explainthatstuff.com/motion.html">motion </a>, if air gives an upward force to a plane, the plane must give an (equal and opposite) downward force to the air. So a plane also generates lift by using its wings to push air downward behind it. That happens because the wings aren't perfectly horizontal, as you might suppose, but tilted back very slightly so they hit the air at an angle of attack . The angled wings push down both the accelerated airflow (from up above them) and the slower moving airflow (from beneath them), and this produces lift. Since the curved top of the airfoil deflects (pushes down) more air than the straighter bottom (in other words, alters the path of the incoming air much more dramatically), it produces significantly more lift.

How airfoil wings generate lift#2: The curved shape of a wing creates an area of low pressure up above it (red), which generates lift. The low pressure makes air accelerate over the wing, and the curved shape of the wing (and the higher air pressure well above the altered air stream) forces that air into a powerful downwash, also pushing the plane up. This animation shows how different angles of attack (the angle between the wing and the incoming air) change the low pressure region above a wing and the lift it makes. When a wing is flat, its curved upper surface creates a modest region of low pressure and a modest amount of lift (red). As the angle of attack increases, the lift increases dramatically too—up to a point, when increasing drag makes the plane stall (see below). If we tilt the wing downward, we produce lower pressure underneath it, making the plane fall. Based on <a dir="ltr" href="https://www.youtube.com/watch?v=dY3daNK1Tek" rel="noopener">Aerodynamics </a>, a public domain War Department training film from 1941.

You might be wondering why the air flows down behind a wing at all. Why, for example, doesn't it hit the front of the wing, curve over the top, and then carry on horizontally? Why is there a downwash rather than simply a horizontal "backwash"? Think back to our previous discussion of pressure: a wing lowers the air pressure immediately above it. Higher up, well above the plane, the air is still at its normal pressure, which is higher than the air immediately above the wing. So the normal-pressure air well above the wing pushes down on the lower-pressure air immediately above it, effectively "squirting" air down and behind the wing in a backwash. In other words, the pressure difference that a wing creates and the downwash of air behind it aren't two separate things but all part and parcel of the same effect: an angled airfoil wing creates a pressure difference that makes a downwash, and this produces lift.

Now we can see that wings are devices designed to push air downward, it's easy to understand why planes with flat or symmetrical wings (or upside-down stunt planes) can still safely fly. As long as the wings are creating a downward flow of air, the plane will experience an equal and opposite force—lift—that will keep it in the air. In other words, the upside-down pilot creates a particular angle of attack that generates just enough low pressure above the wing to keep the plane in the air.

Generally, the air flowing over the top and bottom of a wing follows the curve of the wing surfaces very closely—just as you might follow it if you were tracing its outline with a pen. But as the angle of attack increases, the smooth airflow behind the wing starts to break down and become more turbulent and that reduces the lift. At a certain angle (generally round about 15°, though it varies), the air no longer flows smoothly around the wing. There's a big increase in drag, a big reduction in lift, and the plane is said to have stalled . That's a slightly confusing term because the engines keep running and the plane keeps flying; stall simply means a loss of lift.

Photo: How a plane stalls: Here's an airfoil wing in a wind tunnel facing the oncoming air at a steep angle of attack. You can see lines of smoke-filled air approaching from the right and deviating around the wing as they move to the left. Normally, the airflow lines would follow the shape (profile) of the wing very closely. Here, because of the steep angle of attack, the air flow has separated out behind the wing and turbulence and drag have increased significantly. A plane flying like this would experience a sudden loss of lift, which we call "stall." Photo courtesy of <a dir="ltr" href="https://www.nasa.gov/langley/images/" rel="noopener">NASA Langley Research Center </a>.

Planes can fly without airfoil-shaped wings; you'll know that if you've ever made a paper airplane—and it was proved on December 17, 1903 by the Wright brothers. In their original "Flying Machine" patent (<a dir="ltr" href="https://patents.google.com/patent/US821393" rel="noopener">US patent #821393 </a>), it's clear that slightly tilted wings (which they referred to as "aeroplanes") are the key parts of their invention. Their "aeroplanes" were simply pieces of cloth stretched over a wooden framework; they didn't have an airfoil (aerofoil) profile. The Wrights realized that the angle of attack is crucial: "In flying machines of the character to which this invention relates the apparatus is supported in the air by reason of the contact between the air and the under surface of one or more aeroplanes, the contact-surface being presented at a small angle of incidence to the air ." [Emphasis added]. Although the Wrights were brilliant experimental scientists, it's important to remember that they lacked our modern knowledge of aerodynamics and a full understanding of exactly how wings work.

Not surprisingly, the bigger the wings, the more lift they create: doubling the area of a wing (that's the flat area you see looking down from above) doubles both the lift and drag it makes. That's why gigantic planes (like the C-17 Globemaster in our top photo) have gigantic wings. But small wings can also produce a great deal of lift if they move fast enough. To produce extra lift at takeoff, planes have <a dir="ltr" href="http://en.wikipedia.org/wiki/Flap_(aircraft)" rel="noopener">flaps </a>on their wings they can extend to push more air down. Lift and drag vary with the square of your speed, so if a plane goes twice as fast, relative to the oncoming air, its wings produce four times as much lift (and drag). <a dir="ltr" href="https://www.explainthatstuff.com/helicopter.html">Helicopters </a>produce a huge amount of lift by spinning their rotor blades (essentially thin wings that spin in a circle) very quickly.

Now a plane doesn't throw air down behind it in a completely clean way. (You could imagine, for example, someone pushing a big crate of air out of the back door of a military transporter so it falls straight down. But it doesn't work quite like that!) Each wing actually sends air down by making a spinning vortex (a kind of mini tornado) immediately behind it. It's a bit like when you're standing on a platform at a railroad station and a high-speed train rushes past without stopping, leaving what feels like a huge sucking vacuum in its wake. With a plane, the vortex is quite a complex shape and most of it is moving downward—but not all. There's a huge draft of air moving down in the center, but some air actually swirls upward either side of the wingtips, reducing lift.

Photo: Newton's laws make airplanes fly: A plane generates an upward force (lift) by pushing air down toward the ground. As these photos show, the air moves down not in a neat and tidy stream but in a vortex. Among other things, the vortex affects how closely one plane can fly behind another and it's particularly important near airports where there are lots of planes moving all the time, making complex patterns of turbulence in the air. Left: Colored smoke shows the wing vortices produced by a real plane. The smoke in the center is moving downward, but it's moving upward beyond the wingtips. Right: How the vortex appears from below. White smoke shows the same effect on a smaller scale in a <a dir="ltr" href="https://www.explainthatstuff.com/windtunnel.html">wind tunnel </a>test. Both photos courtesy of NASA Langley Research Center.

Steering anything—from a skateboard or a bicycle to a car or a jumbo jet—means you change the direction in which it's traveling. In scientific terms, changing something's direction of travel means you change its velocity , which is the speed it has in a particular direction. Even if it goes at the same speed, if you change the direction of travel, you change the velocity. Changing something's velocity (including its direction of travel) means you accelerate it . Again, it doesn't matter if the speed stays the same: a change in direction always means a change in velocity and an acceleration. Newton's laws of motion tell us that you can only accelerate something (change its speed or direction of travel) by using a force—in other words, by pushing or pulling it somehow. To cut a long story short, if you want to steer something you need to apply a force to it.

Photo: Steering a C-17 plane by banking at a steep angle. Photo by Russell E. Cooley IV courtesy of <a dir="ltr" href="https://www.af.mil/News/Photos/igphoto/2000657814/" rel="noopener">US Air Force </a>.

Another way of looking at steering is to think of it as making something stop going in a straight line and start going in a circle. That means you have to give it what's called a <a dir="ltr" href="https://www.explainthatstuff.com/centrifuges.html">centripetal force </a>. Things that are moving in a circle (or steering in a curve, which is part of a circle) always have something acting on them to give them centripetal force. If you're driving a car round a bend, the centripetal force comes from friction between the four tires and the road. If you're cycling around a curve at speed, some of your centripetal force comes from the tires and some comes from leaning into the bend. If you're on a skateboard, you can tilt the deck and lean over so your weight helps to provide centripetal force. In each case, you steer in a circle because something provides the centripetal force that pulls your path away from a straight line and round into a curve.

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