nce4 lesson 14,15

TextProject/nce4text.txt

+Lesson 14
+
+世界上最好的两三天以上的天气预报具有很强的猜测性，如果超过六七天，天气预报就没有了任何价值。
+原因是蝴蝶效应。对于小片的恶劣天气--对一个全球性的气象预报员来说，小 可以意味着雷暴雨和暴风雪--任何
+预测的质量会很快下降。错误和不可靠性上升，接踵而来的是一系列湍流的征状，从小尘暴和风暴发展到只有卫星
+上可以看到的席卷整个大陆的旋涡。
+现代气象模型以一个坐标图来显示，图中每个点大约是间隔60英里。即使是这样，有些开始时的资料也不得不依靠
+推测，因为地面工作站和卫星不可能看到地球上的每一个地方。假设地球上可以布满传感器，每个相隔1英尺，并按
+1英尺的间隔从地面一直排列到大气层的顶端。再假定每个传感器都极端准确地读出了温度、气压、温度和气象学家
+需要的任何其他数据。在正午时分，一个功能巨大的计算机搜集了所有的资料，并算出在每个点上12：01 时
+可能出现的情况。
+计算机无法推断出1个月以后的某一天，新泽西州的普林斯顿究竟是晴天还是雨天。正午时分，传感器之间的距离会
+掩盖计算机无法知道的波动--任何偏离平均值的变化。到12：01时，那些波动就已经会在1英尺远的地方造成偏差。
+很快这种偏差会增加到10英尺的范围，如此等等，一直到全球的范围。
+
+
+Beyond two or three days, the world's best weather forecasts are speculative, and beyond six 
+or seven they are worthless.
+The Butterfly Effect is the reason. For small pieces of weather -- and to a global forecaster, small can 
+mean thunderstorms and blizzards -- any prediction deteriorates rapidly. Errors and 
+uncertainties multiply, cascading upward through a chain of turbulent features, from dust 
+devils and squalls up to continet-size eddies that only satellites can see.
+The modern weather models work with a grid of points of the order of sixty miles apart, and 
+even so, some starting data has to guessed, since ground stations and satellites cannot see 
+everywhere. But suppose the earth could be covered with sensors spaced one foot apart, 
+rising at one-foot intervals all the way to the top of the atmosphere. Suppose every 
+sensor gives perfectly accurate readings of temperature, pressure, humidity, and any 
+other quantity a meteorologist would want. Precisely at noon an infinitely powerful 
+computer takes all the data and calculates what will happen at each point at 12:01, 
+The computer will still be unable to predict whether Princeton, New Jersey, will have sun or 
+rain on day one month away. At noon the spaces between the sensors will hide fluctuations 
+that the computer will not know about, tiny deviations from the average. By 12:01, those 
+fluctions will already have created small errors one foot away. Soon the errors will have multiplied 
+to the ten-food scale, and so on up to the size of the globe.
+
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+
 Lesson 15
 
 有两个因素严重地妨碍工业中科学研究的效率 一是科研工作中普遍存在的保密气氛 二是研究人员缺乏个人自由。