時(shí)差N小時(shí):為什么天空不是統(tǒng)一的藍(lán)色 Why The Sky Is Not Blue

Look at various parts of the sky on a clear day andyou will see that it is not a uniform blue.

抬頭仰望天空，你會(huì)發(fā)現(xiàn)在晴朗的日子里，天空并不會(huì)呈現(xiàn)出統(tǒng)一的藍(lán)色。

Even if the sky is deep blue when you look straightup, near the horizon it is lighter.

即使你頭頂上正對(duì)的這片天是深藍(lán)色的，靠近地平線處的也會(huì)相對(duì)較淺一些。

This is partly due to pollution, but even in thecleanest air the sky is lighter near the horizon due tothe effect of earth's atmosphere on sunlight.

部分原因要?dú)w咎于污染，但是就算是在最干凈的空氣中，貼近地平線處的天空顏色也會(huì)比較淺，這是由于地球大氣層對(duì)陽(yáng)光的影響。

When the rays of sunlight enter the atmosphere,the atmosphere tends to deflect the light fromits straight-line path from the sun to the earth, and spread it around the sky, a process that iscalled scattering.

當(dāng)太陽(yáng)光線進(jìn)入到大氣層時(shí)，大氣層會(huì)使陽(yáng)光直行進(jìn)入的路線產(chǎn)生偏離，并使光線散布于天空中，這個(gè)過(guò)程就叫做散射。

If all the colors were spread equally the sky would look white, since all of the colors of lightcombined make white light.

如果所有顏色的光線都均勻分散開來(lái)，那么天空看上去就會(huì)是白色的，因?yàn)樗蓄伾墓饩€組合起來(lái)就是白光。

But the atmosphere does not spread all colors equally in all parts of the sky, and that is whythe sky is not a uniform color.

但是大氣層不會(huì)把所有顏色的光線均勻分布在整個(gè)天空中，這就是為什么天空看上去不是統(tǒng)一的顏色的原因。

The color that is most readily spread is blue.

最容易發(fā)生散射的是藍(lán)色的光。

So when we look up on a clear day we see blue sky,since the sunlight has had to pass throughthe least atmosphere, and fewer of the other colors of light have been spread.

由于陽(yáng)光能夠穿透最薄的大氣層，并且只有少量顏色的光會(huì)發(fā)生散射，因此在晴朗的天氣里，我們看到天空呈現(xiàn)出的就是藍(lán)色。

However, closer to the horizon the sunlight must pass through more of the atmosphere before itreaches our eyes.

然而，在越靠近地平線的地方，陽(yáng)光在進(jìn)入我們的視野之前必須要穿過(guò)的大氣層也就越厚。

This gives the rays of other colors of light a chance to be spread so that the light reaching oureyes is more a mixture of all the colors and therefore appears lighter.

這就為其他顏色的光發(fā)生散射提供了機(jī)會(huì)。這樣一來(lái)，進(jìn)入我們視線的陽(yáng)光就更像是所有顏色的光的混合體，因此會(huì)看上去會(huì)比較淺一些。