The Butterfly Effect 1 蝴蝶效应

Beyond two or three days, the world's best weather forecasts are speculative, and beyond six or seven they are worthless.
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。

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 continent-size eddies that only satellites can see.
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徵状，从小尘暴和暴风发展到只有卫星上可以看到的席卷整块大陆的旋涡。

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.
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。既使是这样，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。

New words and expressions 生词和短语

forecast
n. 预报
speculative
adj. 推测的
blizzard
n. 暴风雪
deteriorate
v. 变坏
multiply
v. 增加
cascade
v. 瀑布似地落下
turbulent
adj. 狂暴的
dust devil
小尘暴，尘旋风
squall
n. 暴风
eddy
n. 旋涡
grid
n. 坐标方格
sensor
n. 传感器