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  • If you ever find yourself gazing at falling snow,

    如果你曾經看著白雪飄落並想著

  • why not catch a few snowflakes on your glove and examine their shapes?

    何不抓住一些雪花放在手套上看看它們是什麼形狀?

  • You might notice that they look symmetrical, and if you look closely, you'll see they have six sides.

    你可能會發現它們是對稱狀的,如果你看得更仔細,你會發現它們具有六個邊

  • You could say a snowflake is simply frozen water,

    當然你可以說雪花不過是結凍的水

  • but compare one with an ice cube from the freezer,

    但與冷凍庫中的冰塊相比

  • and you'll realize they're very different things.

    你會發現雪花其實是非常不一樣的東西

  • Unlike ice cubes, formed when liquid freezes into a solid,

    不像冰塊是由液態水結凍成為固態

  • snowflakes form when water vapor turns straight into ice.

    雪花是由水蒸氣直接結凍成冰

  • But that still doesn't explain why snowflakes have six sides.

    但這仍無法解釋雪花為何是六邊形

  • To understand that,

    為了瞭解這點

  • we need to delve deeper into the physics of water.

    我們要更深入探討水的物理性質

  • Water is made out of two hydrogen atoms and one oxygen atom.

    水是由兩個氫原子加上一個氧原子構成

  • A single water molecule thus has ten protons and ten electrons,

    因此,單一水分子便有十個質子以及十個電子

  • eight from oxygen and one from each hydrogen atom.

    其中八個屬於氧原子,其餘兩個分別屬於兩個氫原子

  • The two electrons from oxygen's outer shell are shared with two electrons from both hydrogens as they bond together,

    與氫原子鍵結時,氧原子外層中的兩個價電子會與氫原子共享

  • and the remaining four outer shell electrons from oxygen form two pairs.

    於是氧原子的外層便剩下四個電子,成為兩個電子對

  • We call the bonds between these atoms covalent bonds.

    我們將這些原子 (氫與氧) 之間的鍵結稱為共價鍵

  • The pairs of electrons are all negatively charged.

    電子對帶有負電荷

  • Similar charges repel,

    同電荷會互斥

  • so they tend to stay as far away from each other as possible.

    因此電子對會盡可能地遠離彼此

  • The pairs form four electron clouds,

    所有的電子對形成四個電子雲

  • two of which are where the hydrogen and oxygen share electrons.

    其中兩個由氫氧之間共享的電子形成

  • The repulsion between the unbonded pairs is even stronger than repulsion between the shared pairs,

    而未鍵結的電子對之間的斥力,遠比形成共價鍵的電子對之間的斥力來得強

  • so the two hydrogens get pushed a little further to an angle of 104.5 degrees.

    因此兩個氫原子會被稍微推擠到,使兩共價鍵夾的角度成為 104.5 度

  • The water molecule as a whole is electrically neutral,

    水分子整體是電中性的

  • but oxygen gets a larger share of electrons,

    但是電子會傾向於靠近氧原子 (氧電負度較高)

  • making it slightly negative and the hydrogens slightly positive.

    使得氧原子方向的電荷偏負 (負偶極),氫原子方向的電荷偏正 (正偶極)

  • Due to its negative charge,

    由於電荷偏負的緣故

  • the oxygen in one molecule is attracted to the positive charge of the hydrogen in another molecule.

    水分子中的負偶極會被另一個水分子中正偶極吸引

  • And so a weak bond between the two molecules,

    於是兩個分子間便產生了微弱的鍵結

  • called a hydrogen bond, is formed.

    也就是所謂的氫鍵

  • When water freezes, this bonding occurs on repeat,

    當水結凍時,氫鍵不斷生成

  • ultimately forming a hexagonal structure

    最後形成六邊形的結構

  • due to the angle between hydrogens and oxygen within each molecule.

    這是由每個水分子中氫原子和氧原子所夾的角度所造成

  • This is the seed of a snowflake,

    這便是雪花的核心

  • and it retains a hexagonal shape as it grows.

    接著雪花便會依此六邊形逐漸增大

  • As the snowflake moves through the air,

    當雪花飄在空氣之中時

  • water vapor molecules stick to the six sharp edges

    水蒸氣會依附在六邊形的邊緣

  • and expand the snowflake outwards, bit by bit.

    一點一點的逐漸增加雪花的體積

  • A snowflake's developing shape depends on atmospheric conditions,

    雪花最終的形狀取決於大氣的狀態

  • like humidity and temperature.

    像是濕度以及溫度等

  • As a snowflake falls,

    隨著雪花的飄落

  • changes in weather conditions can affect how it grows,

    氣象條件的改變也會影響其形狀

  • and even small differences in the paths two snowflakes take will differentiate their shapes.

    甚至只要路徑上一丁點的不同,就會在兩片雪花的形狀之間造成差異

  • However, since conditions at the six sharp edges of one snowflake are similar,

    然而,因為所有雪花的核心都是六邊形

  • a symmetric snowflake can grow.

    所以,所有的雪花都是對稱狀的

  • Weather conditions affect snow on the ground, as well.

    氣象條件也會影響地面上的雪花

  • Warmer ground temperatures produce a wetter snow that is easier to pack

    較溫暖的地面溫度產生的雪較濕軟,更容易堆疊

  • because liquid water molecules help snowflakes stick to each other.

    因為液態的水分子會幫助雪花抓住彼此

  • Melted snow also plays a critical role in another wintry activity, skiing.

    融化的雪對另一項冬季活動也有很大的影響,那就是滑雪

  • Completely dry snow is very difficult to ski on,

    完全乾燥的雪地是非常難滑的

  • because there's too much friction between the jagged snowflakes and the ski surface.

    因為雪花不平整的表面與滑雪板之間的摩擦力太高

  • So what's happening is that as skis move,

    那麼,滑雪時究竟發生了些什麼事呢?

  • they rub the surface of the snow and warm it up,

    滑雪板與雪面相互摩擦並產生熱

  • creating a thin layer of water, which helps them slide along.

    融出了一層水來幫助滑雪板前進

  • So technically, it's not really snow skiing,

    因此,嚴格來說,這其實不是在滑雪

  • but water skiing.

    而是在滑水

  • But it is true that no matter how hard you look,

    千真萬確的一點是,不論你看得如何仔細

  • you're almost definitely not going to find two identical snowflakes,

    你幾乎不可能找出兩片完全一樣的雪花

  • and that's a mystery that scientists are still trying to solve,

    這項謎團仍有待科學家們來解答

  • though we know that it has to do with the many possible branching points in snowflake formation,

    目前我們知道的是,這可能和「雪花形成時可能產生分支的節點」有關

  • and the differences in temperature and humidity,

    另外溫度和濕度的差異也有影響

  • and while we wait for the answer,

    在我們等待答案的同時

  • we can enjoy watching these tiny fractals falling from the sky.

    可以一邊欣賞這些小小的結晶緩緩地由空中落下

If you ever find yourself gazing at falling snow,

如果你曾經看著白雪飄落並想著

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B2 中高級 中文 美國腔 TED-Ed 雪花 氫原子 電子 六邊形 分子

【TED-Ed】雪花的科學 (The science of snowflakes - Maruša Bradač)

  • 12198 1353
    Yun Ting 發佈於 2016 年 02 月 29 日
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