Source：科學60秒
Date：2009.07.21
Summary
《自然物理》雜誌上的一項研究顯示，雨滴的大小分佈是根據大雨滴下落時的解體情況而變化的。A study in the journal Nature Physics shows that raindrop size distribution is a function of large drops disintegrating as they fall.
Raindrop Sizes Surprises
When you get caught in a downpour, you probably don’t think about the size of the raindrops that assault you as you run for cover. But physicists do. And they’ve come to the conclusion that the drops that hit the ground, or your head, are the shattered remains of bigger drops that fell from the clouds. Raindrops come in a variety of sizes, even within the same storm. And scientists used to think that, to get that kind of distribution, raindrops must crash into each other on the way down, breaking up into smaller droplets or coalescing into larger ones. Now a team of French scientists has produced high-speed footage of falling water droplets. And they find that drops of different dimensions don’t require collision—they come from the fragmentation of individual, isolated droplets. Their results appear online in the journal Nature Physics.* The video evidence reveals that water droplets first flatten out as they fall. And as these plummeting pancakes get wider and thinner they eventually capture air, forming what look like little plastic grocery bags floating in a breeze. And when the bags get big enough, they pop. And you’re left wondering why you can never remember your umbrella.
Audio
Words
disintegrate：[dɪsˈɪntɪgreɪt] 使某物碎裂，崩裂
downpour：[ˈdaʊnpɔ:(r)] 傾盆大雨
assault：[əˈsɔ:lt] 攻擊，襲擊，進攻
shatter：[ˈʃætə(r)] 破碎，碎裂，砸碎
coalesce：[ˌkəʊəˈles] 聯合，合併
collision： [kəˈlɪʒn] 碰撞，衝突
fragmentation： [ˌfræɡmen'teɪʃn] 分裂，破碎
flatten out： [ˈflætn aut] 變平，轉為水平飛行，逐漸變平，停止增長
plummet：[ˈplʌmɪt] 垂直落下，驟然跌落
pancake： [ˈpænkeɪk] 烙餅，薄煎餅，粉餅
Relavent
For photos and more info, see Trickle-Down Theory: Simplified Model Gives a New Explanation for How Raindrops Form*(Scientific American is part of the Nature Publishing Group.)https://www.scientificamerican.com/article/raindrop-size-physics/
Website address
https://www.scientificamerican.com/podcast/episode/raindrop-sizes-surprises-09-07-21/
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