鸟类到底能飞多高？
字幕摘录
| 时间 | 英文 | 中文 |
|---|---|---|
| 0:00 | In 1973, an airliner struck a bird called a Ruppel's griffin vulture, which on its | 1973年,一架客机击中了一只叫鲁佩尔的金刚秃鹰的鸟,在它身上 |
| 0:06 | own isn't that weird. | 自己也没那么奇怪 |
| 0:07 | Planes hit birds pretty regularly during takeoffs and landings. | 飞机在起飞和着陆时经常撞击鸟类。 |
| 0:10 | But this collision happened at a cruising height of over 11,000 meters. | 但这次碰撞发生在超过11000米的十字路口高度上. |
| 0:14 | That's way above the height at which most birds fly. | 这比大多数鸟类飞行高度还高 |
| 0:17 | Which makes me wonder, what is the highest a bird can actually fly? | 这让我怀疑 一只鸟能飞的最高点是什么? |
| 0:22 | Hi, I'm Cameron and this is MinuteEarth. | 嗨,我是卡梅伦,这里是"地球" |
| 0:25 | Birds don't tend to fly higher than they absolutely need to, for the same reason you | 鸟儿不会飞得比它们绝对需要的还要高 出于同样的原因 |
| 0:29 | don't sprint when you could walk. | 走路的时候不要冲刺 |
| 0:31 | It's difficult and tiring. | 难且累. |
展开字幕全文（98 条）
| 序号 | 英文 | 中文 |
|---|---|---|
| 1 | In 1973, an airliner struck a bird called a Ruppel's griffin vulture, which on its | 1973年,一架客机击中了一只叫鲁佩尔的金刚秃鹰的鸟,在它身上 |
| 2 | own isn't that weird. | 自己也没那么奇怪 |
| 3 | Planes hit birds pretty regularly during takeoffs and landings. | 飞机在起飞和着陆时经常撞击鸟类。 |
| 4 | But this collision happened at a cruising height of over 11,000 meters. | 但这次碰撞发生在超过11000米的十字路口高度上. |
| 5 | That's way above the height at which most birds fly. | 这比大多数鸟类飞行高度还高 |
| 6 | Which makes me wonder, what is the highest a bird can actually fly? | 这让我怀疑 一只鸟能飞的最高点是什么? |
| 7 | Hi, I'm Cameron and this is MinuteEarth. | 嗨,我是卡梅伦,这里是"地球" |
| 8 | Birds don't tend to fly higher than they absolutely need to, for the same reason you | 鸟儿不会飞得比它们绝对需要的还要高 出于同样的原因 |
| 9 | don't sprint when you could walk. | 走路的时候不要冲刺 |
| 10 | It's difficult and tiring. | 难且累. |
| 11 | So we can't necessarily get the answer to this question through observation. | 因此我们不一定能通过观察得到这个问题的答案. |
| 12 | I mean, I guess we could drop a bunch of birds out of airplanes and see what happens, but | 我的意思是,我想我们可以把一群鸟 离开飞机,看看会发生什么,但 |
| 13 | our AdSense revenue definitely isn't going to cover that. | 我们的AdSense收入绝对无法抵挡 |
| 14 | Plus, we're not monsters. | 而且,我们不是怪物。 |
| 15 | So let's use our understanding of aerodynamics, scaling laws, and biology to science our way | 因此,让我们利用我们对空气动力学,缩放定律和生物学的理解来科学我们的方式 |
| 16 | to an approximate answer. | 对一个大概的答案。 |
| 17 | There are two things that limit how high a bird can fly. | 有两件事限制鸟儿能飞多高. |
| 18 | Its ability to stay aloft as the air pressure decreases, and, on a much more basic level, | 随着气压的降低 它能保持高度 而在更基本的水平上 |
| 19 | its ability to stay alive as the temperature and amount of oxygen decreases. | 随着气温和氧气量的下降,它能够活着。 |
| 20 | So first, let's figure out which bird could survive at the highest altitude. | 所以首先,让我们找出哪只鸟能在最高海拔生存. |
| 21 | Oxygen supplies birds the energy they need to stay warm, but at higher altitudes there's | 氧气为鸟类提供维持温暖所需的能量 但在更高的海拔高度 |
| 22 | less oxygen available and the temperature is much colder. | 氧气少 温度更冷。 |
| 23 | So a bird's ability to survive high up in the air depends on how efficiently they use | 所以鸟类在空中生存的能力 取决于它们的效率 |
| 24 | oxygen and how well they can retain body heat. | 氧气,以及它们能保持多好的体温。 |
| 25 | This paper measured the oxygen use of a handful of birds and found that, very generally, their | 这篇论文测量了少数鸟类的氧气使用,发现非常普遍地,它们的氧气用量是: |
| 26 | overall oxygen use increases with mass. | 总的氧气使用量随着质量的增加而增加。 |
| 27 | We can then adjust according to other traits, like how much energy their flight muscles | 我们可以根据其他特征来调整 就像飞行肌肉的能量 |
| 28 | require and how much insulation their feathers provide. | 他们的羽毛需要和多少绝缘 |
| 29 | From all of this, we can calculate the altitude at which each bird should suffer from hypothermia. | 由此我们可以计算出每只鸟体温低的高度。 |
| 30 | Let's call this their popsicle point. | 我们把这叫做冰棒点 |
| 31 | If we then compile a data set of flying birds and plug their data into these equations, | 如果我们再编集飞行鸟类的数据集 并将其数据插入这些方程中 |
| 32 | we can see a general pattern emerge. | 我们可以看到一个总体模式出现。 |
| 33 | Larger birds can theoretically survive at higher altitudes than smaller birds. | 较大型的鸟类理论上可以在比小型鸟类更高的高度生存. |
| 34 | There are exceptions, of course, this is biology after all, but our calculations suggest that | 当然也有例外 这毕竟是生物学 但我们的计算表明 |
| 35 | there are a bunch of birds that could potentially survive above 10,000 meters, and the largest | 有一群鸟可能生存在 10000米以上,最大的 |
| 36 | bird in our data set, the wandering albatross, might be able to survive as high as 17,000 meters. | 鸟类在我们的数据集, 流浪的信天翁, 可能能够生存到17,000米。 |
| 37 | But remember, we also need to figure out if any of these birds could actually stay aloft | 但记住,我们还需要 找出这些鸟 是否真的可以保持高度 |
| 38 | at such high altitudes. | 在这么高的高度上 |
| 39 | Because the air is less dense the higher you go, less air is available at higher altitudes, | 因为空气密度越低越高 高空的空气就越少 |
| 40 | to push upward against a bird's wings and create that lift. | {\fn华文仿宋\fs16\1cHD1D1D1}把鸟的翅膀往上推,然后制造起升力 |
| 41 | A bird's ability to stay aloft high in the air depends on its weight, size of its wings, | 鸟在空气中保持高度的能力取决于它的重量,翅膀的大小, |
| 42 | and the shape and angle of attack of its wings. | 以及其翅膀攻击的形状和角度. |
| 43 | That's a factor called the lift coefficient. | 这是一个叫做升力系数的因素。 |
| 44 | Combining all of that tells us how much lift a bird's wings should generate in still air | 综合所有这一切告诉我们 鸟的翅膀在空气中会产生多少 |
| 45 | at a given altitude. | 在一个特定的高度。 |
| 46 | Simple enough at first, but while weights and wingspans and whatnot are easy enough | 一开始很简单,但重量和翅膀 和一些不简单 |
| 47 | to measure, the wings' shapes and angles aren't, because a bird's wing shape changes | 要测量,翅膀的形状和角度不是, 因为鸟的翅膀形状改变 |
| 48 | as it flies. | 当它飞翔。 |
| 49 | I'll save you the long explanation of my rationale here, and just say that this is | 我会给你留一个长长的解释 来解释我的理由 |
| 50 | about where I go out on a bit of a limb. | 关于我在哪里出去 一点点的肢体。 |
| 51 | The lift coefficient for the birds in our data set peaks at about 1.5 or so, and that's | 我们数据集中鸟类的升降系数 大约在1.5左右,这就是 |
| 52 | when they're taking off or about to stall. | 当他们起飞或 即将拖延。 |
| 53 | In other words, when the bird is trying hardest to generate lift. | 换句话说,当鸟类最努力生成升力时. |
| 54 | And since staying aloft is likely a struggle at a bird's maximum altitude, this is probably | 由于留在高空可能是在鸟类最高高度上挣扎,所以这可能是 |
| 55 | a pretty good estimate of the lift coefficient at this point. | 对升力系数的估算还不错 |
| 56 | From there, we can find the lowest air pressure at which each bird could generate sufficient | 从那里,我们可以找到最低气压 在每个鸟类产生足够的。 |
| 57 | lift to keep its mass aloft, and then use our friend the barometric equation to convert | 升降机保持质量高度 然后使用我们的朋友 微量方程转换 |
| 58 | those numbers to altitudes to estimate the highest point each bird in our data set should | 我们数据集中每只鸟的最高点 |
| 59 | be able to actually maintain flight. | 能够维持飞行 |
| 60 | Let's call this their lift limit. | 我们把这叫做升降限吧 |
| 61 | In general, the smaller birds have the highest lift limits. | 一般来说,较小的鸟类的升力极限最高. |
| 62 | The hulking mute swan would struggle to generate lift at a mere 3,800 meters, while the puny | 笨手笨脚的天鹅在3800米高处 很难产生升降机 而笨手笨脚的 |
| 63 | sand marten should be able to glide at nearly 19,000 meters. | 沙马腾应该能在近19000米处滑翔. |
| 64 | Of course, air moves and it's not uniformly dense at given altitudes, so there's definitely | 当然,空气在一定的高度上 并不一致 所以绝对有 |
| 65 | some wiggle room here, which will be a surprise tool that's going to help us later. | 这里有些摇摆的房间, 这将是一个惊喜工具 将帮助我们以后。 |
| 66 | But in any case, a bird with a higher lift limit should be able to fly higher than a | 但无论如何,升降限高的鸟类应该能飞得比飞得高 |
| 67 | bird with a lower one. | 鸟的下部。 |
| 68 | Now let's combine our lift limit data with our popsicle point data. | 现在我们把升力极限数据 和冰棒点数据结合起来 |
| 69 | We can see that lots of birds, like the mistlethrush, can theoretically fly super high, but would | 我们可以看到,很多鸟类, 像雾刷, 理论上可以飞超高, |
| 70 | freeze long before they got there. | 在他们到达之前就冻结了 |
| 71 | And then there are a bunch of other birds, like the wandering albatross, that could likely | 还有一堆其他的鸟, 像游荡的信天翁, 可能 |
| 72 | survive at super high altitudes, but wouldn't be able to actually maintain flight up there. | 在超高空生存 但实际上无法维持飞行 |
| 73 | That leaves us with a small cluster of birds with relatively high popsicle points and high | 这给我们留下了一小群鸟类 具有相对较高的冰棒点和高 |
| 74 | lift limits. | 取消限制。 |
| 75 | Mathematically, these should be the highest flying birds. | 在数学上,这些应该是最高的飞行鸟类. |
| 76 | And for the most part, they're geese. | 而多为雁. |
| 77 | The greylag goose, the bean goose, the canada goose, and the bar-headed goose should be | 灰炉鹅,豆鹅,罐田鹅,棒头鹅应该是 |
| 78 | able to fly as high as 8,000 meters or so, according to our calculations, and this matches | 根据我们的计算 能飞到8000米左右 |
| 79 | up pretty well with what scientists have actually observed. | 和科学家实际观测到的相当不错 |
| 80 | Like, during its migration over the highest mountain range on the planet, the bar-headed | 譬如,在它迁徙到地球上最高的山脉时, |
| 81 | goose can reach altitudes of over 7,000 meters. | 鹅可以达到7000米以上的高度. |
| 82 | And then there's the white stork, which, based on its popsicle point and lift limit, | 还有白鹳,根据它的冰球点和升力极限, |
| 83 | is our predicted highest flying bird. | 是我们预测的最高飞鸟 |
| 84 | It could potentially fly up to about 10,500 meters. | 它有可能飞到约10500米。 |
| 85 | In reality, it doesn't fly anywhere near that high. | 在现实中 它不会飞到那么高的地方 |
| 86 | But remember, birds don't necessarily fly as high as they might be physically capable of. | 但记住,鸟类的飞行 不一定能达到体能的高度 |
| 87 | But wait, what about the rupus griffin? | 等等,那暴风雨怎么办? |
| 88 | A bird we know for a fact can fly higher than 11,000 meters. | 据我们所知,一只鸟的飞行高度可超过11,000米。 |
| 89 | Our math suggests that it has lift limited a lot lower than that, about 8,200 meters. | 我们的数学显示,它的升力比它低很多,大约8200米。 |
| 90 | But this is where theoretical calculations fall short without some additional real-world | 但这就是理论计算不足的地方 没有额外的现实世界 |
| 91 | knowledge. | 知识。 |
| 92 | See, the rupus griffin likes to soar on thermals, warm columns of rising air that can help birds | 你看,暴风雨的贪婪 喜欢在热量,温暖的升起的气柱 能够帮助鸟类 |
| 93 | exceed their mathematical lift limit, sometimes even thousands of extra meters up into the air. | 超过他们的数学升力极限, 有时甚至数千米额外的升入空气。 |
| 94 | Other birds are also known to ride thermals, but none of the other high popsicle point | 其它鸟类也被称为热力飞行 但其他高冰柱点都没有 |
| 95 | birds ride such supercharged thermals. | 鸟儿骑着这种超充电热。 |
| 96 | So the rupus griffin is likely the bird capable of the highest flight. | 因此鲁普斯格里夫芬可能是能够飞行最高的鸟类. |
| 97 | With the right thermal, it might even reach its very generous popsicle point of 15,000 meters. | 有了正确的热量,它甚至可能达到非常慷慨的15,000米冰棒点. |
| 98 | Turns out, that bird might have had a lot of climbing left to do. | 原来那只鸟可能还有许多爬行余地 |
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