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  • If we wanted to make a cloud entirely from scratch, we’d first need a fleet of jumbo

    如果你想徒手製造一朵雲,我們需要一整群噴射機

  • jets or several hundred hot-air balloons to haul hundreds of tons of water up to the sky.

    或幾百顆熱氣球,把幾百噸的水運上天空。

  • And then, somehow, we’d need to disperse all that liquid into a mist of droplets small

    然後我們得把這麼多水噴成小到足以漂浮的水滴。

  • enough to float. In short, it wouldn’t be easy. And yet,

    簡單來講,這真不簡單。但同時,

  • our atmosphere manages to pump out one cloud after another all over the world at altitudes

    我們的大氣層在世界各地升起一朵又一朵的雲,

  • of up to 20 kilometers above sea level, using water and fuel carried all the way from Earth’s

    高度可達海拔20公里,完全只用來自地表的水和動力。

  • surface. Cumulus clouds, for example get their start

    例如積雲,開始時陽光的能量切斷水分子間的連結,

  • when solar energy evaporates water from oceans, plants, and soil by breaking the bonds that

    例如積雲,開始時陽光的能量切斷水分子間的連結,

  • hold water molecules together. As the patch of air above collects moisture and heat cooler,

    讓海、植物和土壤中的水蒸發。 上方的空氣有了濕度和熱能,

  • heavier air sinks around it pinching it off and pushing it aloft like an invisible hot-air

    較冷、較重的空氣會向下包夾它, 並把它向上推,如同隱形的熱氣球。

  • balloon. Surprisingly, this balloon’s cargo doesn’t weigh it downin fact, the more

    驚人的是,這顆氣球不會因重量而下沉─事實上,

  • water vapor it collects before lift-off, the lighter it gets.

    飄上去的水量越多,氣球還會越輕。

  • As weird as that sounds, it’s because water vapor is a gas just like the nitrogen and

    就是這麼奇怪,因為水蒸氣和氮氣、氧氣(大氣主要成分)

  • oxygen that make up most of the atmosphere. Basic physics dictates that a given volume

    同為氣體,而基本物理指出,相同體積的氣體

  • of gas has the same number of molecules regardless of what those molecules are. And water is

    會有相同數量的分子,無論種類為何。而水是由

  • made of H plus H plus O, which is lighter than both two Ns and two Os. So warm, humid

    兩個氫加一個氧構成,比兩個氮或兩個氧還輕。因此

  • air is even more buoyant than warm, dry air. As the invisible balloon goes up, the falling

    暖濕空氣甚至比暖乾空氣還輕。當隱形氣球上升,

  • pressure outside allows it to keep ballooning, which spreads out its internal heat and lowers

    外界維持氣球邊界的氣壓變小,分散其內部熱能並

  • its temperature. Eventually, the air at the top cools enough for the water vapor there

    使其降溫。最後上端的空氣冷到足以讓水蒸氣凝結,

  • to condense into droplets, which look from afar like a thin wisp of cloud. And as the

    成為小水滴,遠看就像一縷輕雲。當氣球其他部分

  • rest of the balloon rises, water vapor continues to cool and condense at the same altitude,

    繼續上升,水蒸氣繼續冷卻,並在同樣高度凝結,

  • creating a flat-bottomed cloud that appears to grow upward out of nothing.

    形成一片平底雲朵,彷彿無中生有般往上長。

  • What’s more, as the condensing water vapor molecules bond together into liquid droplets,

    另外,當水分子彼此結合,從蒸氣凝結成水滴,

  • they release the energy they absorbed from Earth’s surface when they evaporated. This

    它們會釋放從地表蒸發時所吸收的能量。

  • heats the surrounding pocket of air, giving it lift and sucking more moist air up behind

    這加熱了周遭空氣,讓它上升並吸起更多下方濕空氣,

  • it [updraft], which cools and condenses and releases heat, which fuels lift and strengthens

    濕空氣凝結又釋放熱量,持續驅動並強化上升氣流。

  • the updraft. Even in a small cumulus cloud , the total energy released from condensation

    即使是一小團積雲,凝結釋放的總能量也很巨大─

  • is hugeequivalent to about 270 tons of TNT. And if the supply of water vapor is much

    相當於270噸的TNT。如果水蒸氣的供給更多,

  • larger, the energy released can produce stratosphere-high pillars of cloud with violent updrafts, fierce

    釋放的能量能製造高達平流層的雲柱, 以及猛烈的上升氣流,

  • electrical storms, and grapefruit-sized hailstones. Not good weather for hot air ballooning.

    產生強烈的風暴以及葡萄柚大的冰雹。 我看今日這天不像個玩熱氣球的。

If we wanted to make a cloud entirely from scratch, we’d first need a fleet of jumbo

如果你想徒手製造一朵雲,我們需要一整群噴射機

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B2 中高級 中文 空氣 氣球 熱氣球 釋放 分子 能量

為什麼會有云? (Why Are There Clouds?)

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    Yrchinese 發佈於 2021 年 01 月 14 日
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