英國學生科學讀本 Lesson 89 云和雨(1)
第89課 云和雨
Each of us drinks about three pints of fresh water every day, and we use a great deal of water for washing, for cooking, and for other purposes. Where does all this water come from? In some places we get water from wells, and in other places from rivers or lakes. But from whatever source we get the water, it is quite certain that at one time or another it must have fallen from the clouds as drops of rain.
我們每個人每一天都會飲用3品脫左右的淡水, 而日常生活中的清洗、烹飪與其他諸多活動都離不開用水。這些水都是從哪里來的呢? 在有些地方, 人們從井中取水, 而在另外一些地方, 人們從河流或湖泊中取水。然而, 無論我們從哪里取水, 可以肯定的是, 天上的云朵時不時就會降下雨水。
Have you ever been in a cloud? Perhaps you have climbed to the top of a high hill, and have seen a white cloud come scurrying towards you, till it has covered the hill-top and everything above, below, and around you. The cloud was no longer white, but of a dull grey colour, like the mistwhich we see on a foggy morning. Indeed a fog is simply a cloud resting on the ground.
你看到過云朵嗎? 也許你曾經爬到山峰之上, 看到一塊白云快速朝你飄來, 直到它將山頂與周圍空間中的萬物, 包括你在內, 全部包裹起來。這時, 云朵不再是白色, 它變成了昏暗的灰色, 就像是朦朧的清晨時分天空的那層薄霧。實際上, 霧氣就是落在地面上的云朵。
But what are the clouds made of? They are just like the clouds of white steam, as we call it, that you see rising from a boiling kettle. The white steam and the clouds are both composed of extremely small specks of water, so small that they have been called water-dust. When a number of these water-specks join together, they form a drop of rain, and then the weight of this rain-drop makes it come pattering quickly to the earth.
然而, 云朵究竟由什么構成呢? 其實, 它們與那些從沸騰的水壺中冒出的白色水蒸氣一樣。白色蒸汽與云朵均是由很小的水粒構成, 因為它們的體積實在太小, 所以我們稱之為水霧。當許多水粒凝聚在一起時, 它們就變成了雨滴。隨后, 雨滴的重量使得自己迅速落到了地面。
How did all this water which forms the clouds and the rain get into the air? It was evaporated by the heat of the sun from the surface of the oceans and seas, and rivers and lakes. Three-quarters of the surface of the great globe on which we live is covered with water.
這些構成云朵和雨水的水分是怎樣進入到空氣中的呢? 它們由海洋、河流與湖泊表面的水在太陽熱量的作用下蒸發(fā)而成。在我們生活的這個巨大星球中, 四分之三的表面都被海水所覆蓋。
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