Yaël: Don?
Don: Yes, Yaël?
Y: We've been in this art museum for 5 hours now. And you've spent the whole time staring at that one photograph of sunset.
D: Are you sure?
Y: Of course I'm sure. You haven't budged.
D: But are you sure it's a sunset? It might be a sunrise.
Y: Ah…
D: I wonder if you can tell just by looking at it.
Y: Actually, although there’s no way to tell with certainty, there are a couple of clues you can look for.
D: Really?
Y: Sure. Let’s think about what happens to the atmosphere during the day. It warms up, which means it can hold more moisture, and traffic and other activities churn a certain amount of dust and pollutants into it.
All this extra stuff in the air can make the sunset much redder than sunrise. It can also make the light more diffuse. Artists sometimes remark that the light at sunset is softer and warmer than the sharp light at sunrise.
D: That's so?
Y: Yes, although rain or other weather can disrupt this pattern. Another clue is the ground, which cools down overnight. This can cause dew to condense out of the air, and mist to form in the air near the ground. If there’s any rising mist or dew in your photo, chances are it’s sunrise.
D: OK, then, that means this picture's... Hey, it turned out nights!
Y: The museum is closed, Don. You should have asked me earlier, instead of standing there for 5 hours.
日出還是日落?
Yaël: 我們都已經(jīng)在這個(gè)美術(shù)博物館呆了整整五個(gè)小時(shí)了,你也盯著那張日落的照片看了整整五個(gè)小時(shí)了。
Don: 你確定?
Y: 我當(dāng)然能確定啦。你動(dòng)都沒動(dòng)過。
D: 我是說,你就那么確定這是拍的日落?它也有可能是日出啊。我倒想知道你單憑看照片就能下定論了。
Y: 事實(shí)上呢,雖然說不能完全肯定的進(jìn)行辨別,但是我們還是有兩條線索可循。
D: 真的?
Y: 當(dāng)然。想想白天的時(shí)候空氣會(huì)發(fā)生什么樣的變化??諝獠粩嗌郎?,這就意味著空氣中會(huì)含有更多的水分。另外,交通以及其他的活動(dòng)會(huì)將大量的粉塵及污染物質(zhì)帶入空氣當(dāng)中。
空氣中多出來的水分、粉塵等等物質(zhì)會(huì)使日落看起來比日出顏色更紅。同時(shí),這些物質(zhì)會(huì)讓光線擴(kuò)散得更開。藝術(shù)家們有過這樣的評(píng)論——日落時(shí)的光芒相對(duì)于日出時(shí)強(qiáng)烈的光線來說,更為柔和、溫暖。
D: 是這樣啊?
Y: 恩。但是,有的時(shí)候下雨或其他的天氣會(huì)對(duì)這種辨別方法有所影響。別擔(dān)心,我們還有另一條線索!這條線索便是土地,晚上,土壤溫度會(huì)慢慢的降低。這樣一來,空氣中便會(huì)凝結(jié)出露珠,為地表蒙上一層薄霧。所以說,如果說照片中有上升的霧氣或是露珠,那么肯定就是日出了。
D: 那么,照這方法來看……嘿,這是日落!
Y: 看吧,博物館都要關(guān)門了。你該早些問我這個(gè)問題的,也不至于在這里站上整整5個(gè)小時(shí)了。