字幕列表 影片播放 列印英文字幕 Ok, here's a little riddle for you – they're long, white, and you can see them in the sky. What is it? I used to think it was Old Man W inter farts. But no. If you answered contrails from a jet, then you're the winner! But what causes them? Let's find out! Ever noticed how on a cold day, you see your own puff of breath when you exhale? The exact same thing happens to a plane. The temperature at 25,000 feet or higher, which is cruising altitude, is really low, around -30 degrees Fahrenheit. While the engine burns the fuel, it releases different substances (mostly water and carbon dioxide) into the atmosphere. The cold air condenses, and sometimes even freezes the hot exhaust fumes, creating those white “tails” which look a lot like smoke. That’s why they’re often called "condensation trails", or contrails. To give you an idea, planes like the Boeing 747 eject around 2 gallons of water every 3 seconds! That’s a lot of water to condense! Ok, but why are these contrails sometimes long and sometimes short? Well, this depends on the weather. Long contrails form in humid conditions, while low humidity makes them much shorter. And that’s how these white lines can help you predict the weather. If you see long contrails, it might mean that a storm is coming. If a plane leaves short lines then don’t worry: the weather will be good. Even though traveling by plane is common nowadays, these huge steel birds are still surrounded by secrets and myths that give birth to a lot of questions. Pardon the pun, but it’s high time to get more answers! 1. Why can’t planes fly when it’s extremely hot? Hot air is less dense than cool air. This means the air molecules are spread further apart from each other, so they come into contact with the plane’s wings less. As a result, it’s harder for a plane to take off. It’d need a higher take-off speed, which would require a longer runaway. Besides, planes rely on different internal machinery, and a good part of it already runs hot. That’s why, when the temperature is 120 Fahrenheit or higher, the plane might be delayed, since the possibility of overheating the electronics is dangerous. 2. Can a plane fly on one engine? Yes, it can! Especiaily if it has one engine. Ha ha. Okay, even though, thanks to technological improvements, engine failures have become pretty rare, they still happen sometimes due to damage. However, losing an engine in-flight isn’t even considered a serious problem by pilots. This is mainly because planes that fly over oceans, or for long-distance routes, have special certificates that indicate the exact time they can operate safely with one engine. For example, the Boeing 787 can fly around 330 minutes without the second engine. 3. Do planes’ oxygen masks have only 15 minutes of air? Yes, they do, but that’s enough for an emergency. If the cabin is depressurized at a high altitude, the passengers won’t be able to breathe, so they use oxygen masks. At the same time, the pilot will start descending right away to get lower than 10,000 feet, where it’s possible to breathe normally again. And this descent won’t take longer than 15 minutes. 4. What are those white spiral marks on airplane engines? These spirals of different sizes and shapes are for the safety of the ground crew. The ground crew has to wear hearing protection, so they can't hear the roaring engines of a plane. But when they see the spirals swirling, they know it's not safe to approach the area. Also, these spiral marks help to tell which plane is about to take off if there are several of them on the ground. 5. Is there the “safest” seat on an airplane? Most airlines claim that the safest seat is just a myth. But statistics of airplane crashes beg to differ. They say that this seat is at the back. If you happen to sit near the tail of a plane, you're about 40% more likely to survive a crash than those in the front. If you need a more specific answer, it’s the middle seats in the rear section. 6. Why are there black triangles inside a plane’s cabin? These black stickers are located on about four windows in a cabin. Each of them is aligned with the edge of the wings. If a flight attendant believes there might be something wrong with the moving parts of the wings – slats or flats – they know exactly which window provides the best view to check them. Also, you should choose a seat between those triangles if you tend to get motion sickness. The plane’s center of gravity is at the wings, so you’ll have a smoother trip. 7. Why are airplane windows round? Actually, at the beginning of the commercial flying era, they were square. But after some time, airlines started flying at higher altitudes, requiring the cabin to be pressurized. But the frequent pressurization and depressurization caused the window corners to deform and even break. Turned out, round windows can withstand the pressure of cruising altitude much better. So, square windows were soon replaced for good. 8. Why does the plane’s food taste bad? Apart from the fact that, on board, you’ll get only defrosted dishes which’ve lost a big part of their flavor, the pressurization of the cabin is to blame. The air in the cabin might be drier than a desert, literally. And this numbs a lot of your taste buds. Besides, quite often the cabin air can cause your nasal cavities to swell, making the food taste even more unappealing. 9. Is it possible to avoid turbulence? Turbulence is disturbances in airflow. The causes can vary; some by weather conditions, some – by cumulonimbus clouds, which actually are also weather conditions. While it’s impossible for planes to steer clear of turbulence altogether, pilots do a lot to lessen it by bypassing areas of heavy turbulence for passengers’ comfort. But if you’re a nervous flyer, here’s a tip for you – choose morning flights, because the air is less bumpy at this time. Do you think flying is scary? Let me know in the comments! 10. Why do your ears pop during flying? Ears pop because there’s a rapid change in pressure when a plane reaches a cruising altitude or lands. There’s not enough time for the pressure inside the inner ear and the air pressure outside to equalize. And the air trapped inside your inner ear causes the eardrum to pop. If you don’t want ear-popping to turn into pain, try chewing gum or yawing to help your eardrums adjust faster. This is also the reason you’ll sometimes hear babies crying during the descent. They have a hard time equalizing their ears. 11. Are a plane’s tray tables the dirtiest things on board? Sadly, tray table surfaces have eight times more bacteria than the lavatory flush buttons. Unfortunately, quite often, cleaning crews don’t have enough time between flights to take care of everything properly. So, don’t forget to wipe the tray table down with a sanitizing wipe, and don’t let your food sit on it. By the way, seat pockets and seatbelt buckles are almost as dirty. 12. What citizenship does a baby born on board get? There’re several options. A newborn can become the citizen of the country where the airline is registered; the country over which they were born; or the country where the plane landed. The decision is usually made by the airline, depending on the laws of the countries involved. However, the first option is the most common. Sometimes such babies get a bonus from the airline –a free first-class trip to any part of the world on their 18th birthday. 13. Why are most planes white? First, because extra paint would add around 1200 pounds to its weight. And the heavier the plane, the more fuel it burns. Airlines simply don’t want to pay the extra money. Also, the white color keeps a plane cool by reflecting sunlight. And there are safety reasons: it’s easier to spot any cracks, damage, or oil spills on a white surface. Plus, in case of a crash, the white fuselage will be able to attract the rescuer’s attention faster. 14. Why are there no parachutes on board? Putting one on and jumping out of the plane correctly is no easy feat. You probably wouldn’t be able to do it in an emergency situation. Training for skydivers requires many hours, in which they learn all the details about handling a parachute and how to land safely. What’s more, even the most experienced skydivers don’t jump from an altitude higher than 15,000 feet. On top of that, adding just parachutes (without helmets and supplemental oxygen) for all passengers would mean making a plane 8,000 pounds heavier. Hey long ago, I used to wear my sport parachute in the airliner, because I didn’t want to check it as luggage. I still remember the looks the other passengers gave me. Boy that was fun! Hey, if you learned something new today, then give the video a like and share it with a friend! And here are some other cool videos I think you'll enjoy. Just click to the left or right, and stay on the Bright Side of life!
B1 中級 為什麼飛機後會有白色的痕跡? (Why There Are White Trails After a Plane) 2 0 林宜悉 發佈於 2021 年 01 月 14 日 更多分享 分享 收藏 回報 影片單字