为什么冷冻反而能防止结冰
字幕摘录
| 时间 | 英文 | 中文 |
|---|---|---|
| 0:00 | What if I told you that one of the best ways to keep something from freezing is to freeze it? | 如果我告诉你 防止冰冻的最好方法之一是冻结它呢? |
| 0:05 | In this video, I'm going to show you one of the weirdest effects in physics. | 在这部视频中,我要向大家展示物理学中最奇特的效果之一. |
| 0:10 | Freezing water releases heat. | 冻水释放热量. |
| 0:12 | We're going to see why this happens and how it can mean the | 我们要看看为什么会这样 以及这是什么意思 |
| 0:15 | difference between an entire orchard surviving or freezing to death during a late winter storm. | 整个果园在冬季风暴后期存活或冻死之间的差别。 |
| 0:21 | This year in April, late freezing temperatures in the western United States caused a complete | 今年四月,美国西部的晚冷气温 导致美国西部地区 |
| 0:26 | loss of many fruit orchards due to the fruit blossoms freezing in the sub-zero temperatures. | 许多果园在零度以下的温度下因果实开花而消失。 |
| 0:32 | However, I had heard that there's a technique that farmers sometimes use where they'll spray | 不过,我听说有种技术 农民有时会用来喷雾 |
| 0:36 | water on their crops to cover them with a layer of ice in order to somehow protect them from freezing. | 他们的庄稼上有水,用一层冰覆盖他们, 以某种方式保护他们免受冰冻。 |
| 0:43 | This seems very counterintuitive. | 这似乎非常反感。 |
展开字幕全文（218 条）
| 序号 | 英文 | 中文 |
|---|---|---|
| 1 | What if I told you that one of the best ways to keep something from freezing is to freeze it? | 如果我告诉你 防止冰冻的最好方法之一是冻结它呢? |
| 2 | In this video, I'm going to show you one of the weirdest effects in physics. | 在这部视频中,我要向大家展示物理学中最奇特的效果之一. |
| 3 | Freezing water releases heat. | 冻水释放热量. |
| 4 | We're going to see why this happens and how it can mean the | 我们要看看为什么会这样 以及这是什么意思 |
| 5 | difference between an entire orchard surviving or freezing to death during a late winter storm. | 整个果园在冬季风暴后期存活或冻死之间的差别。 |
| 6 | This year in April, late freezing temperatures in the western United States caused a complete | 今年四月,美国西部的晚冷气温 导致美国西部地区 |
| 7 | loss of many fruit orchards due to the fruit blossoms freezing in the sub-zero temperatures. | 许多果园在零度以下的温度下因果实开花而消失。 |
| 8 | However, I had heard that there's a technique that farmers sometimes use where they'll spray | 不过,我听说有种技术 农民有时会用来喷雾 |
| 9 | water on their crops to cover them with a layer of ice in order to somehow protect them from freezing. | 他们的庄稼上有水,用一层冰覆盖他们, 以某种方式保护他们免受冰冻。 |
| 10 | This seems very counterintuitive. | 这似乎非常反感。 |
| 11 | Why would a layer of ice keep your plants from freezing? | 为什么冰层会让你的植物不冻? |
| 12 | Well, if you look this up online, you'll find a lot of people saying that the ice insulates the | 如果你在网上查的话 你会发现很多人说 冰层会绝缘 |
| 13 | But that can't be the reason. | 但这不可能是原因。 |
| 14 | Ice is actually a much better conductor of heat than liquid water. | 冰实际上是比液态水更好的热导体. |
| 15 | So why do some farmers swear by this method? | 那为什么有些农民要用这种方法发誓? |
| 16 | Well, to show you why it helps, | 嗯,为了告诉你为什么它帮助, |
| 17 | I need to stick a water bottle in the freezer and wait. | 我要把水瓶放在冰箱里等着 |
| 18 | Now before we continue, with summer in full swing and so many celebrations happening this year, | 在我们继续之前, 夏天满是秋天, 这么多的庆祝今年, |
| 19 | I want to thank Raycon for sponsoring this video and sending me their bone conduction headphones. | 我想感谢雷康赞助了这段视频 并寄给我他们的骨导耳机 |
| 20 | Whenever I need to hear what's going on around me but still want to listen to music, | 每当我需要听到我周围发生的事情... ...但仍想听音乐, |
| 21 | these are the headphones I use. | 这些是我的耳机。 |
| 22 | Whether it's going for a walk, | 无论它去散步, |
| 23 | doing experiments, or just cleaning up in the lab, they sit right outside of your ears and | 做实验,或者在实验室打扫, 他们就坐在你的耳朵外面 |
| 24 | instead of blocking your ear canal, they use bone conduction. | 而不是堵住你的耳渠, 他们使用骨导线。 |
| 25 | So the sound travels through the | 所以声音会穿过 |
| 26 | vibrations in your bones. | 骨头里有震动 |
| 27 | That means I can listen to music, podcasts, or calls while still hearing | 也就是说我可以一边听音乐一边听播客,一边听电话 |
| 28 | what's going on around me because nothing's blocking my ear canal. | 我周围发生什么了 因为我的耳朵没有堵塞 |
| 29 | And not only is this | 不仅如此 |
| 30 | a cool way to transfer sound signals to your brain, but it's much nicer than regular earphones. | 将声音信号传递到大脑的酷方法,但比普通耳机要好得多. |
| 31 | I can stay aware of traffic, people, or equipment around me without sacrificing sound quality. | 我可以在不牺牲音质的情况下 保持对交通、人员或设备的认识 |
| 32 | They're also built for everyday use. | 也为日常使用而建造. |
| 33 | You can get up to 13 hours of battery life, | 电池寿命可达13小时 |
| 34 | and they're IP68 waterproof and dustproof. | 他们都是IP68防水防尘的 |
| 35 | So sweat, rain, and even sand isn't a problem. | 所以,汗水,雨, 甚至沙子都不是问题。 |
| 36 | And what's nice is the no-bud design stays comfortable and doesn't slip while you move. | 不错的是,无泡泡设计保持舒适,不会在移动时滑倒. |
| 37 | And another nice thing is that Raycon delivers premium performance without the premium price tag. | 还有一件好事是雷康在没有溢价标签的情况下提供溢价性能. |
| 38 | So their quality rivals the big audio brands, but at about half the cost. | 因此,他们的质量与大型音响品牌竞争,但成本约为一半. |
| 39 | Over three million | 300多万 |
| 40 | people already love Raycon, and they back it with a 30-day happiness guarantee. | 人们已经喜欢雷康了 他们用30天的幸福保证来支撑它 |
| 41 | These bone conduction headphones are a great option for everyday listening. | 这些骨导耳机是日常听觉的绝佳选择. |
| 42 | So click the link in the description box or go to buyraycon.com slash the Action Lab BC | 点击描述框中的链接 或去 buyraycon.com 切换动作实验室 BC |
| 43 | to get 20% off. | 得到20%的关机。 |
| 44 | And thanks to Raycon for sponsoring. | 谢谢雷康赞助 |
| 45 | Now let's get back to our experiment. | 现在,让我们回到我们的实验。 |
| 46 | Now the goal here is to cool down this water until it drops well below 32 degrees Fahrenheit | 现在的目标是冷却这水 直到它下降到32华氏度以下 |
| 47 | or zero degrees Celsius. | 或零摄氏度。 |
| 48 | Now we'll check it a bit later here, and you can see that it's | 现在我们待会再查,你可以看到 |
| 49 | well below freezing temperature now, but the water is still liquid. | 已经低于冰冻温度了 但水还是液体 |
| 50 | Now the reason it's still liquid | 现在原因仍然是液体 |
| 51 | is because water doesn't freeze at 32 degrees or zero degrees Celsius. | 是因为水不会在32摄氏度或零摄氏度时结冰。 |
| 52 | That's just the point | 这就是重点 |
| 53 | at which it can freeze. | 在那里它可以冻结。 |
| 54 | The temperature at which water has to freeze is about negative 40 degrees | 水冷却温度约为负40度 |
| 55 | which just so happens to be negative 40 degrees Fahrenheit. | 正好是华氏40度的负值 |
| 56 | So for once in my life, | 所以,在我的一生中, |
| 57 | the world can be united about the temperature scale. | 世界可以团结在温度尺度上。 |
| 58 | So if water can freeze at zero degrees | 如果水能以零度结冰 |
| 59 | Celsius, but it doesn't have to freeze until about negative 40 degrees, then what's this | 摄氏度,但它不必冻结 直到负40度, 那么这是什么 |
| 60 | in-between region? | 区域之间? |
| 61 | Well, this is the supercooled region. | 这是超级冷却区 |
| 62 | Thermodynamically speaking, in this region, | 热力学说,在这个区域, |
| 63 | the water would rather be a solid than a liquid. | 水是固体而不是液体 |
| 64 | But the problem is that it first has to make a | 但是问题在于它首先必须做到 |
| 65 | first tiny ice crystal, and that takes a little bit of energy. | 第一小冰晶 这需要一点能量 |
| 66 | It's kind of like an activation | 有点像激活 |
| 67 | energy for a chemical reaction. | 用于化学反应的能量。 |
| 68 | But once that first tiny crystal forms, the rest of the ice | 但一旦第一个小结晶形成 剩下的冰块 |
| 69 | can grow easily. | 可以轻松成长. |
| 70 | Now one way to lower this activation energy is to give the ice a surface | 现在降低这种激活能量的方法之一 就是给冰表面 |
| 71 | {\fn黑体\fs22\bord1\shad0\3aHBE\4aH00\fscx67\fscy66\2cHFFFFFF\3cH808080}然后开始编队 {\fn黑体\fs22\bord1\shad0\3aHBE\4aH00\fscx67\fscy66\2cHFFFFFF\3cH808080}然后开始 | |
| 72 | Instead of having to make a tiny sphere of ice floating in the middle of water, | 而不是在水中漂浮着冰块 |
| 73 | it can simply start growing on the surface, so only about 180 degrees. | 它可以在表面开始生长 所以只有180度左右 |
| 74 | That takes less energy, | 这需要更少的精力, |
| 75 | and if that surface has tiny scratches or imperfections, you can get an even smaller | 如果表面有微小的划痕或不完美, 你可以得到更小的 |
| 76 | angle that it has to form, and so it takes even less energy. | 因此它需要更少的能量。 |
| 77 | So rough surfaces tend to form ice | 粗糙的表面会形成冰 |
| 78 | more easily than smooth ones. | 比平滑的还容易 |
| 79 | Another thing that lowers this activation energy, of course, | 当然,还有一件事会降低激活能量 |
| 80 | is temperature. | 是温度。 |
| 81 | The colder the water gets, the easier it is for that first ice crystal to form. | 水越冷,第一个冰晶就更容易形成. |
| 82 | Eventually, once you get down to about negative 38 to negative 40 degrees, the barrier becomes so | 最终,一旦你下降到 大约负38到负40度, 屏障变得如此 |
| 83 | small that the normal random collisions of water molecules are enough to create the first ice | 小于水分子的正常随机碰撞足以产生第一个冰 |
| 84 | crystal almost instantly. | 晶体几乎瞬间。 |
| 85 | But above that temperature, it's really just a waiting game. | 但是在温度以上,它真的只是一个等待游戏。 |
| 86 | Eventually, by random chance, enough molecules will get enough energy and come together in the | 最后,通过随机的偶然性, 足够的分子会得到足够的能量 并聚集在其中 |
| 87 | right way to form that first ice crystal, but it might take seconds or hours. | 形成第一个冰晶的正确方法 但可能需要几秒钟或几小时 |
| 88 | So that's where we | 这就是我们 |
| 89 | are with our water bottle right now. | 我们的水瓶现在。 |
| 90 | If I take supercooled water like this and pour it on ice | 如果我把超级冷水 像这样倒在冰上 |
| 91 | crystals, then it doesn't need any activation energy, so it spontaneously forms ice at the | 晶体,那么它不需要任何激活能量, 所以它自发地形成冰在 |
| 92 | {\fn黑体\fs22\bord1\shad0\3aHBE\4aH00\fscx67\fscy66\2cHFFFFFF\3cH808080}我倒在地上 {\fn黑体\fs22\bord1\shad0\3aHBE\4aH00\fscx67\fscy66\2cHFFFFFF\3cH808080}我倒在地上 | |
| 93 | Also, if I take the supercooled water and hit it, I can give it its | 而且,如果我拿 超级冷水打它,我可以给它 |
| 94 | activation energy to form ice, and the whole thing can suddenly freeze. | 激活能量形成冰块,整件事会突然冻结. |
| 95 | Now this is pretty cool and | 现在这很酷 |
| 96 | all, but what does it have to do with keeping plants alive during a freeze? | 但是这和植物在冰冻期间生存有什么关系? |
| 97 | Well, I mentioned | 我提到过 |
| 98 | that liquid water needs a bit of energy to make that very first ice crystal. | 液态水需要一点能量 才能形成第一个冰晶 |
| 99 | It needs to get over | 它需要结束 |
| 100 | that initial bump, but after that, it's all downhill. | 最初的颠峰,但在那之后, 这一切都是下坡。 |
| 101 | It actually releases energy when it | 它会释放能量 |
| 102 | turns from a liquid into a solid. | 从液体变成固体 |
| 103 | So yes, you heard that right. | 是的,你说得对。 |
| 104 | Ice formation is exothermic. | 冰的形成具有排出性. |
| 105 | It releases heat. | 它释放热量。 |
| 106 | Although this sounds counterintuitive, it actually makes sense | 虽然这听起来反直觉,但实际上有道理 |
| 107 | when you think about it. | 当你想到它。 |
| 108 | What do you have to do to make ice from water? | 你要怎么做才能从水中制冰? |
| 109 | You have to continually | 你必须不断 |
| 110 | remove heat. | 清除热量。 |
| 111 | If you don't remove the heat, you get no ice. | 不除热则无冰. |
| 112 | So that should mean that if I can measure | 如果我能衡量的话 |
| 113 | the temperature of this water bottle, when it suddenly turns to ice, it should warm up. | 这个水瓶的温度, 当它突然变成冰, 它应该热起来。 |
| 114 | So let's try it here. | 所以,让我们试试这里。 |
| 115 | Whoa. | 珃 |
| 116 | And look at that. | 看那个 |
| 117 | It gets warmer. | 变暖了 |
| 118 | It actually warms up by about | 其实是暖和的 |
| 119 | 10 degrees Fahrenheit. | 十度华严. |
| 120 | So it gets back to 32 degrees Fahrenheit or zero degrees Celsius, | 因此它回到32华氏度或零摄氏度, |
| 121 | exactly the equilibrium freezing point of water. | 正是水的平衡冻结点 |
| 122 | Let's try it again. | 师再试. |
| 123 | So you can see my liquid | 这样你就能看到我的液体了 |
| 124 | bottle on the left here is next to another bottle that already started to freeze. | 左边的瓶子是另一个已经开始冻结的瓶子的旁边. |
| 125 | So that bottle's | 所以那个瓶子 |
| 126 | 32 degrees Fahrenheit. | 三十二度华严. |
| 127 | You can see how it's much warmer than the one that hasn't frozen yet. | 你可以看到它有多温暖 比一个还没有冰冻。 |
| 128 | But | 不过 |
| 129 | now if I hit the liquid water bottle, you can see it instantly releases heat and warms up to 32 | 现在,如果我击中液态水瓶, 你可以看到它立即释放热量,热度高达32 |
| 130 | degrees. | 学位。 |
| 131 | Oh, look at that. | 哦,看看那个。 |
| 132 | Whoa. | 珃 |
| 133 | This is just so mind blowing to me. | 这让我心烦意乱 |
| 134 | It seems so wrong to see water | 看见水似乎很不对劲 |
| 135 | heat up when it's freezing. | 寒冷时加热. |
| 136 | Now my water bottles could only get to about 20 degrees Fahrenheit | 现在我的水瓶只能达到20华氏度 |
| 137 | before they started freezing, but pure water should be able to get to much lower temperatures | 但纯水应该能降低温度 |
| 138 | before it's forced to freeze. | 在它被迫冻结之前。 |
| 139 | So I wanted to see how close I could get to this theoretical | 所以我想看看我有多接近这个理论 |
| 140 | limit of negative 40 degrees. | 负40度限制。 |
| 141 | If I reduce my water drop size, I'm statistically less likely | 如果我减少水量,统计学上我更不可能 |
| 142 | to have many nucleation sites. | 拥有许多核子化网站。 |
| 143 | Also, if I make the interface that the water is touching a liquid as | 而且,如果我做接口 水触摸液体 |
| 144 | well, then it'll avoid nucleation sites. | 那么,它会避免核子化网站。 |
| 145 | So what I'm going to do is put some small drops of distilled | 所以,我要做的是放一些小滴蒸馏 |
| 146 | water on this Petri dish of mineral oil, and then I'll set the dish on some dry ice. | 这个Petri的矿油盘上的水 然后把盘子放在干冰上 |
| 147 | So it'll start | 开始吧 |
| 148 | to cool down. | 冷静下来。 |
| 149 | This oil will drop to way lower temperature than negative 40 degrees, but let's | 这种油会下降到比负40度更低的温度 但让我们 |
| 150 | see how close the water drops can get to that theoretical point of negative 40. | 看水滴有多接近 理论上的负40。 |
| 151 | But how do I | 但是,我怎样 |
| 152 | know when they're freezing with these tiny drops? | 知道这些小滴冰冻的时候吗? |
| 153 | Well, remember that freezing water releases heat | 记得冻水释放热量 |
| 154 | like I just showed. | 就像我刚刚展示。 |
| 155 | So I can know exactly when they freeze if I see a sudden hot spot. | 这样我就能知道他们什么时候冻结 如果我看到一个突然的热点。 |
| 156 | So I'll | 我会的 |
| 157 | measure the temperature of the liquid with my IR camera. | 用我的IR相机测量液体的温度。 |
| 158 | And what I expect to see is tiny hot | 我期望看到的是微小的热量 |
| 159 | spots pop up whenever a drop freezes. | 滴滴冻结时会出现斑点。 |
| 160 | So let's see what happens. | 因此,让我们看看会发生什么。 |
| 161 | Whoa. | 珃 |
| 162 | Okay, the first drop just | 好吧,第一滴刚刚 |
| 163 | froze. | 冻结。 |
| 164 | And we see a little hot spot show up that brought it back up to 32 degrees for that specific | 我们看到一个小热点出现, 它把它带回了32度 对于具体 |
| 165 | drop. | 下来。 |
| 166 | There's another one. | 还有一个 |
| 167 | Another one. | 又一个. |
| 168 | Okay, the last one finally froze. | 好吧,最后一个终于冻结了。 |
| 169 | I was able to get to about | 我终于知道 |
| 170 | negative 20 degrees Fahrenheit before the last drop froze. | 在最后一滴之前,华氏20度 |
| 171 | So now we're starting to understand | 现在我们开始明白 |
| 172 | how putting liquid water on something during below freezing temperatures could protect it. | 如何在温度低于冰冷时 将液态水放上它 |
| 173 | As that water starts to freeze, it releases heat that keeps it at 32 degrees, and it won't drop | 当水开始结冰时,它释放出热量,使其保持在32度,不会下降 |
| 174 | below that temperature. | 温度以下。 |
| 175 | So water that's turning into ice is like a little heater that keeps | 因此,水变成冰 就像一个小热器保持 |
| 176 | whatever it is on at 32 degrees. | 无论它是什么 在32度。 |
| 177 | So as long as there is ice forming on the plant, the plant itself | 只要植物上结冰 植物本身 |
| 178 | cannot be below freezing. | 不能低于冰冻。 |
| 179 | So let's see how well this actually works. | 让我们来看看这到底有多有效。 |
| 180 | So I went out and cut some | 于是我出去切了一些东西 |
| 181 | from my yard that are identical. | 从我院子里一样的。 |
| 182 | I'm going to put them in the freezer, but the one on the left I'm | 我要把它们放进冰箱,但是左边那个我 |
| 183 | going to spray with pure water. | 喷上纯水。 |
| 184 | And I'm spraying this with ice water, so it's not going to help | 我用冰水喷这个 所以没用的 |
| 185 | it because it's warming it up at all. | 因为它的暖化 它的完全。 |
| 186 | The water is already freezing temperatures. | 水已经冷冻的温度。 |
| 187 | So let's see | 所以让我们看看 |
| 188 | if this actually helps. | 如果这真的有用的话。 |
| 189 | Okay, I'm going to wait about five minutes here. | 好吧,我在这里等5分钟 |
| 190 | Okay, let's check the | 好吧,让我们检查一下 |
| 191 | temperatures now. | 现在温度。 |
| 192 | Whoa, look at that. | 哇,看看那个。 |
| 193 | Look how much warmer the one that I sprayed with water is. | 你看,多温暖 我喷的水是。 |
| 194 | So I can see solid water on here. | 这样我就能看见这里的固体水。 |
| 195 | Now let's warm these up and see which plant actually froze. | 现在,让我们热热这些 看看哪个植物实际上冻结了。 |
| 196 | So the one that had solid ice on it didn't freeze. | 所以那个有坚固的冰块 并没有结冰 |
| 197 | So ice protects plants from freezing. | 所以冰能保护植物免于冰冻 |
| 198 | It really is true. | 这是真的。 |
| 199 | But before you go spraying all your plants with water right during a freeze, | 但是在冷冻期间 去喷洒你的植物之前 |
| 200 | this method isn't foolproof. | 这种方法不是万无一失的 |
| 201 | Once you no longer have any liquid turning to ice, | 一旦你不再有液体变成冰 |
| 202 | then the plant will continue to drop in temperature, even with the ice on it. | 植物会继续降温 即使上面有冰块 |
| 203 | For example, in this experiment, I did the same thing except I let all the water freeze, | 例如,在这个实验中,我做了同样的事情 除了我让所有的水冻结, |
| 204 | leaving the flowers at negative temperatures for a long time. | 长时间以负温离开花朵. |
| 205 | And in this case, both flowers died. | 而在这种情况下,两朵花都死了. |
| 206 | Also, if you live in a dry climate, sometimes the act of spraying the plants can make it worse | 还有,如果你生活在干燥的气候中, 有时喷洒植物的行为会更糟 |
| 207 | because the water evaporates and cools down really quickly. | 因为水蒸发和冷却非常快。 |
| 208 | And then that lands on the plant | 然后它降落在植物上 |
| 209 | cooling it down faster so it could freeze faster as well. | 把它冷却得更快 这样它也能更快地冷却下来 |
| 210 | So overall, this method does help, | 因此,总的来说,这种方法确实有帮助, |
| 211 | but it's like an art of when and how to apply the water to help the plants without making it worse. | 但是它就像一个艺术 何时和如何应用水 来帮助植物 而不让它更糟。 |
| 212 | So let me know in the comments section if you've ever used a method like this to save your plants | 所以,请在评论部分告诉我,如果你曾经使用这样的方法来拯救你的植物 |
| 213 | during a freeze. | 在冻结期间。 |
| 214 | And thanks for watching another episode of the Action Lab. | 感谢您观看另一集的动作实验室。 |
| 215 | I hope you learned | 我希望你学过 |
| 216 | something. | 东西。 |
| 217 | If you haven't subscribed to my channel yet, remember to hit that subscribe button and | 如果你还没有订阅我的频道, 记得点击订阅按钮, |
| 218 | we'll see you next time. | 下次见 |
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