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  • You've probably heard different explanations for why leaves change color: lower temperatures, less daylight, less rain.

    Scientific American Instant Egghead你也許聽過關於葉子為什麼會變色 的不同解釋低溫 比較少的日照

  • But, the correct answer is: less daylight.

    匱乏的雨水但是正確的答案是

  • Temperature can affect the intensity of leaf color, which I will explain in a minute, but less daylight actually causes color change.

    比較少的日照溫度能夠影響 葉子變色的程度

  • Most leaves contain chlorophyll, a green pigment that starts the process of photosynthesis.

    待會我就會解釋但是較短的日照才是葉子變色的原因 大多數葉子都含有葉綠素

  • Chlorophyll helps convert sunlight, carbon dioxide and water into sugars that travel to the branches and the roots, feeding the tree.

    它是一種綠色的色素

  • Chlorophyll breaks down and is replenished all summer long.

    能夠使得光合作用開始進行

  • As daylight hours shorten, however, veins that bring water and nutrients to the leaf gradually close off.

    葉綠素幫忙植物把陽光、二氧化碳、還有水轉換成在枝幹以及根中被傳輸的醣類

  • The old chlorophyll disappears, and no new chlorophyll forms.

    讓樹因而得到養分在整個夏天,葉綠素不斷分解

  • The green color fades.

    然後又被補足

  • Yellow and orange pigments, which were there all along, become visible.

    但當日照時數開始縮短的時候

  • But what about the red colors?

    為葉子帶來水分跟營養的葉脈

  • They actually form during the fall.

    會逐漸關閉

  • As veins close, sugars get trapped in the leaf.

    就這樣,舊的葉綠素消失之後

  • They react with other chemicals to form the red pigments.

    不會有新的葉綠素補足綠色也因而褪去

  • You'll remember I said intensity is connected to temperature.

    另一方面,一開始就存在的

  • If days are bright, and nights are cold, more sugars get trapped, and the reds intensify.

    黃色和橘色色素就這樣變得明顯 那紅色又從何而來?

  • Eventually, the drier autumn weather triggers a hormone telling the tree to drop its leaves.

    它們其實是在秋天形成的

  • Otherwise, the leaves would use up water that the tree needs to keep its roots alive during the winter.

    當葉脈關閉之後,醣類會被困在葉子中

  • Okay, what about evergreens?

    在與化學物質作用之後

  • The needles have a waxy coating, and less surface area, which reduces water loss.

    就會形成紅色色素如果你還記得,我說過溫度會影響變色程度

  • They also contain a chemical like anti-freeze, so the roots and the leaves can survive the winter.

    這是因為如果白天很晴朗,而夜晚很冷的話會有更多的醣類被困住

  • Now that you know the science behind colorful autumn leaves, let's identify some of them:

    秋葉的紅色因而加深最後,秋天乾燥的天氣

  • Oaks turn red and brown.

    會促使一種激素的產生,它會告訴樹該掉葉子了

  • Hickories turn bronze;

    不然的話,葉子會用掉太多的水分

  • Aspen and poplar turn gold and yellow;

    這樣在冬天的時候,根部就沒有足夠的水分維生

  • Sugar maples turn orange;

    好吧,那長青樹呢?

  • Black maples turn yellow;

    它們的針狀葉有蠟質覆蓋

  • And red maples turn -- what else?-- brilliant red.

    還有比較少的表面積

  • For Scientific American's Instant Egghead,

    因此能減少水分的散失

  • I'm Mark Fischetti.

    它們也有一種像防凍劑的化學物質

You've probably heard different explanations for why leaves change color: lower temperatures, less daylight, less rain.

Scientific American Instant Egghead你也許聽過關於葉子為什麼會變色 的不同解釋低溫 比較少的日照

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B1 中級 中文 美國腔 葉子 水分 醣類 色素 紅色 關閉

【科學知識】你知道為什麼秋天葉子會變色嗎? Why Do Autumn Leaves Change Color? (Why Do Autumn Leaves Change Color? - Instant Egghead #51)

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    Ashley Chen 發佈於 2015 年 09 月 25 日
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