為什麼冬天會呼出「白霧」? Why Can You See Your Breath When It’s Cold Out?

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	為什麼冬天會呼出「白霧」? Why Can You See Your Breath When It’s Cold Out? Why Can You See Your Breath When It’s Cold Out? 作者 Nick Kembel 本圖文出處: MP3: 為什麼冬天會呼出「白霧」?   Why Can You See Your Breath When It’s Cold Out? 空氣中的溼度愈高，你呼出的氣就愈能被看見。 目錄 / More to Learn / 中文翻譯(& 答案) 科普園地         Have you ever been in such cold weather that you could see your breath? Did you feel as though you were a mythical creature emitting a cloud of mist each time you breathed out? Well, sorry to ruin your fantasy, but there’s a scientific explanation for this fascinating phenomenon.         As you probably already know, every time you inhale, your lungs absorb oxygen from the air. When you exhale, your lungs put carbon dioxide (CO2) back into the air. The warm air released from your body with each exhalation contains vapor because of the moisture from your lungs, throat, and mouth. The warmth gives the particles of water the energy they need to keep moving rapidly. But when the air outside is cold, the water particles slow down and move closer together, forming little drops of water in the air, which is a process referred to as condensation. These drops of water suspended in the air appear like a cloud under lights, which is why you are able to see them.         How cold does it need to be for you to witness this phenomenon? Actually, there’s no set answer. It depends on other factors, such as the humidity level of the air—the more humid the air, the more visible your breath will be. But generally speaking, you can usually see your breath when the temperature reaches around 7°C or cooler. One tip to see it more easily is to open your mouth wide and exhale from deeper in your throat so that the air coming out will be warmer and carry more vapor.         So, the next time the mercury in the thermometer plummets, step outside, take a deep breath, exhale, and enjoy the spectacle! 1. Which of the following words in the passage means “the transformation of a gas into a liquid”? (A) Spectacle. (B) Exhalation. (C) Phenomenon. (D) Condensation. 2. Which of the following statements is true about the air exhaled from the human body? (A)  It stops moving if the temperature is too low. (B)  It contains a large amount of oxygen. (C)  It is a gas and normally not visible. (D)  It is completely dry and warm. 3. According to the passage, under which circumstances will you be less likely to see your breath? (A)  Breathing out air on a freezing rainy day. (B)  Releasing your breath when the weather is chilly. (C)  Blowing out your breath when the temperature is below 0°C. (D) Taking a deep breath under the sunlight and expelling it from the nose. 答案：1.D 2.C 3.D 單字片語整理 Words in Use ● particle [ˋpɑrtɪk!] n. 微粒；粒子 ● suspend [səˋspɛnd] vt. 中斷，中止；吊銷（執照）；垂掛，懸掛 ● absorb [əbˋsɔrb] vt. 吸收；理解 ● witness [ˋwɪtnɪs] n. 證人 vt. 目擊 ● humidity [hjuˋmɪdətɪ] n. 溼氣，溼度 ● transformation [͵trænsfɚˋmeʃən] n. 變形，轉型 ● vapor [ˋvepɚ] n. . 蒸氣 ● thermometer [θɚˋmɑmətɚ] n. . 溫度計 ● spectacle [ˋspɛktək!] n. . 奇觀 ● mythical [ˋmɪθɪkəl] a. 神話的；虛構的 ● emit [ɪˋmɪt] vt. 發出，散發 ● exhalation [͵ɛksəˋleʃən] n. 呼出 ● condensation [͵kɑndɛnˋseʃən] n. 凝結 ● mercury [ˋmɝkjərɪ] n. 水銀 ● expel [ɪkˋspɛl] vt. （從體內或容器內）排出 ● plummet [ˋplʌmɪt] vi. 驟降，暴跌 Practical Phrases ● generally speaking 一般而言 = in general ● carbon dioxide 二氧化碳 Plants absorb carbon dioxide and produce oxygen. 植物吸收二氧化碳並且製造氧氣。 ● take a deep breath 深呼吸 I always take a deep breath before going on the stage. 我每次上臺前都會深呼吸。 ● be referred to as... 被稱作⋯⋯ The president of the US is sometimes referred to as the chief executive. 美國總統有時被稱作最高行政首長。 ● as though + S + V 好像／彷彿⋯⋯ Tina acts as though she’s tough. In fact, she is quite timid. 蒂娜表現得好像她很強悍。其實，她膽小如鼠。 More to Learn breathe [ brið ] vi. 呼吸 breathe out 呼氣 breathe in 吸氣 • The beginner practices how to breathe under water using scuba equipment. 那位初學者練習如何在水下使用浮潛設備呼吸。 以下介紹其他與「呼吸，呼氣」相關的動詞用法: a. inhale [ ɪnˋhel ] vi. & vt. 吸入 exhale [ ɛksˋhel ] vi. & vt. 呼出(空氣) • If you inhale those toxic fumes, you will get sick. 如果吸進那些毒氣，你就會生病。 • Before the match, the player took a deep breath and exhaled to ease his nervousness. 在比賽前，該選手深呼吸然後吐氣來緩解緊張。 b. respire [ rɪˋspaɪr ] vi. 呼吸(正式用法) • To be able to respire underwater, humans need special equipment. 為了能在水下呼吸，人類需要特殊的設備。 c. gasp [ gæsp ] vi. (因驚訝、害怕、疼痛等而)倒抽一口氣/喘息 • I gasped with pain when the nurse gave me a shot. 護士幫我打針時，我痛得倒吸一口氣。 d. pant [ pant ] vi.(因吃力而)氣喘吁吁 • Eddie could not help panting after climbing five floors to the office. 艾迪爬了五層樓到辦公室後累得氣喘吁吁。 中文翻譯(& 答案) 為什麼冬天會呼出「 白霧」? 你曾身處在冷到可以看見自己呼出的氣的寒冷天氣下 嗎?每次呼氣的時候，你是不是覺得自己好像是一隻吐出薄 霧的神獸?嗯，很抱歉破壞你的幻想，但這有趣的現象是有 科學解釋的。 正如你可能已經知道的，每次你吸氣，你的肺就會從空 氣中吸收氧氣。當你吐氣時，你的肺會將二氧化碳排回空氣 中。因為肺部、喉嚨和嘴巴有水分，所以隨著每次呼吸從身 體釋放出的暖氣都含有水蒸氣。氣體的溫度給予水粒子所需 的能量持續快速移動。但當外面的空氣是冷的，水粒子會慢下來並向彼此更靠近，在空氣中形成小水滴，這個過程被稱 為凝結。這些懸浮在空氣中的小水滴在光線下看起來像一團 雲，這就是為什麼你能看得見它們。 那要多冷你才看得見這個現象呢?其實，並沒有固定的 答案。其取決於其他因素，像是空氣中的溼度 ─ 空氣中 的溼度愈高，你呼出的氣就愈能被看見。但一般來說，通常 當氣溫達到約攝氏七度或更冷時，你便能看到你的氣息。想 要更容易看到氣息的一個小訣竅，就是張大嘴巴並從喉嚨的 更深處吐氣，如此一來吐出的氣會更暖並挾帶更多水蒸氣。 所以，下次溫度計裡的水銀驟降時，走出戶外、深呼 吸、吐氣，然後欣賞眼前的奇觀吧! 1. 下列哪一個文中的單字意思是 “the transformation of a gas into a liquid”? (A) 奇觀。 (B) 呼氣。 (C) 現象。 (D) 凝結。 2. 關於人體吐出的氣體，下列敘述何者正確? (A) 如果氣溫太低，它會停止移動。 (B) 它含有大量的氧氣。 (C) 它是氣體且通常看不見。 (D) 它是完全乾燥且溫暖的。 3. 根據本文，在何種情況下你較不可能看到自己的氣息? (A) 在寒冷的下雨天吐氣。 (B) 在冷颼颼的天氣下吐氣。 (C) 在溫度低於攝氏零度時吐氣。 (D) 在陽光下深呼吸並從鼻子吐氣。 題解: 根據本文第三段，溼度高、氣溫低於攝氏七度時 便能看到氣息，若要更容易看到，需從「喉嚨」 的更深處吐氣，以挾帶更多水蒸氣，可知 (D) 的 情況下較不可能看到吐出的氣，故選之。