評論
打印
Sublimation on this moment of science.
今天我們的節目要講的是：升華現象。
Pop quiz, everybody put away your books, and keep your eyeson your own radio.
各位，請放下你們手中的書本，專心聽收音機，我們來做一個突擊測驗。
You fill the ice tray up to the rim and put it in the freezer.
用水將冰格填得滿滿的，漫過冰格的邊緣，然后再將冰格放到冰箱的制冷室里，
Theice that results will be
最后結成的冰會：
at the rim over the rim under the rim.
剛好齊邊 邊緣以上 邊緣以下
Answer? It depends.
答案是要看情況而定。
I know, you hate that.
我明白，你們不喜歡這樣的答案。
But it does depend-it depends on how long you wait before checking onthe ice again.
但是，實際情況確實如此—答案取決于你要過多長時間去查看。
My guess would be that most folks chose answer b: over the rim.
我猜，很多人都會選擇b邊緣以上。
That is correct, ifyou checked on the ice trays after only a couple hours.
如果你在放入制冷室僅兩個小時之后去查看的話，這個答案就是正確的。
That's because water expands when itturns into ice, as you know if you ever put a soda bottle in the freezer and came back to find it exploded all over the fish sticks.
這是因為水在變成冰的時候會膨脹。就像大家所知道的，如果將一瓶汽水放在制冷室中，回頭去看的時候會發現，汽水已經炸開了，整個制冷室中到處都是汽水。
But if you were to leave the ice tray untouched for a couple of months, you might find the ice tobe under the rim, or lower than the water was.
但是，如果你將冰格放在制冷室中，好幾個月都不動它的話，你會發現，冰在邊緣以下，或是低于你之前裝的水的高度。
Huh? Didn't we just say water expands when it freezes? Initially, yes.
哈？我們剛剛不是才說了水在變成冰的時候會膨脹嗎？最開始的時候，會。
But frozen water can dosomething else as well: it can sublimate.
但是冷凍之后的水也會有其他的變化：升華。
To sublimate is to go from one state to another without passing through the usual intermediary state.
升華也就是物質不經中間狀態直接從一個狀態轉變成另一個狀態。
By adding heat, ice can be melted into liquid water, which can be evaporated.
通過加熱，冰可以化成液態水，液態水可以被蒸發為水蒸氣。
That's three states:solid, liquid, gas.
這是三個狀態：固態，液態，氣態。
But given enough time, ice can also turn into a gas without melting first!
但是，如果時間足夠的話，冰可以在不被融化的情況下轉變為氣態。
When your ice cubes seem to have shrunk, it's because they are sublimating:
如果你的冰“縮水”了，那是因為被升華了：
the frozen water is slowlyevaporating off the cubes, without ever actually melting.
在沒有被融化的情況下，固態水以非常緩慢的速度在蒸發著。
Will this work in any freezer? Next time.
這種現象在任何的制冷器中都會出現嗎？下次再談。
