推荐回答(5个)
太阳光是由赤、橙、黄、绿、青、蓝、紫七种光组成的。这七种光中青、蓝、紫波长较短,容易被空气分子和尘埃散射。
为什么天空是蓝的?
我们所看到的蓝天是因为空气分子和其他微粒对入射的太阳辐射中的可见光进行选择性散射的结果。散射强度与微粒的大小有关。当微粒的直径小于可见光波长时,散射强度和波长的4次方成反比,不同波长的光被散射的比例不同,此亦成为选择性散射。当太阳辐射的可见光进入大气后,空气分子和微粒(尘埃、水滴、冰晶等)会将太阳光向四周散射。组成太阳光的红、橙、黄、绿、蓝、靛、紫7种光中,红光波长最长,紫光波长最短。波长比较长的红光透射性最大,大部分能够直接透过大气中的微粒射向地面。而波长较短的蓝、靛、紫等色光,很容易被大气中的微粒散射。以入射的太阳光中的蓝光(波长为0.425μm)和红光(波长为0.650μm)为例,当光穿过大气层时,被空气微粒散射的蓝光约比红光多5.5倍。因此晴天天空是蔚蓝的。但是,当空中有雾或薄云存在时,因为水滴的直径比可见光波长大得多,选择性散射的效应不再存在,不同波长的光将一视同仁地被散射,所以天空呈现白茫茫的颜色。
如果说短波长的光散射得更强,你一定会问为什么天空不是紫色的。其中一个原因就是在太阳辐射的可见光透过大气层时,空气分子对紫色光的吸收比较强,所以我们所观测到的太阳辐射可见光中的紫色光较少,但并不是绝对没有,在雨后彩虹中我们很容易观察到紫色的光。另外一个原因和我们的眼睛本身有关。在我们的眼睛中,有3种类型的接收器,分别称之为红、绿和蓝锥体,它们只对相应的颜色敏感。当它们受到外界的光刺激时,视觉系统会根据不同接受器受到刺激的强弱重建这些光的颜色,也就是我们所看到物体的颜色。事实上,红色锥体和绿色锥体对蓝色和紫色的刺激也有反映,红锥体和绿锥体同时接受到阳光的刺激,此时蓝锥体接收到蓝光的刺激较强,最后它们联合的结果是蓝色的,而不是紫色的。
太阳光里可见光有七种颜色:红、橙、黄、绿、蓝、靛、紫。红光最强,橙、黄、绿也比较强,最弱的是波长短,频率高的蓝、靛、紫。当太阳光透过厚厚的大气层时蓝、靘光的大部分却被大气层扣留下了,它们被大气层里的浮尘、水滴推来搡去,反射来反射去的,结果把大气层“染”成蓝色的了。就是说波长短,频率高的蓝、靛、紫光会更多的参与散射,而散射的结果是蓝光会在各个方向被看见,所以天是蓝的 。
天空本是没有颜色的,由于太阳光的折射,它有了色彩。而这也是夜晚的天空为什么看起来是黑的原因。到了夜晚,太阳光照不到这一半地球的天空,没有了强烈的阳光,天空就没有了色彩,有的,只是黑色。当然咯,也是有月亮和星星的光的,但月亮本不会发光,月亮的光是反射太阳光的,当然不明亮,而星星都离我们太远,于是我们看到的夜空,也就不会像白天的那样亮了
首先了解光的工作原理,光从太阳传播时,像海浪一样上下移动,波长聚集在一起时,我们看起来好像是白色。
我们看到的天空,经常是蔚蓝色的,特别是一场大雨之后,天空更是幽蓝得象一泓秋水,令人心旷神怡。大气本身是无色的。天空的蓝色是大气分子、冰晶、水滴等和阳光共同创作的图景。
阳光进入大气时,波长较长的色光,如红光,透射力大,能透过大气射向地面;而波长短的紫、蓝、青色光,碰到大气分子、冰晶、水滴等时,就很容易发生散射现象。被散射了的紫、蓝、青色光布满天空,就使天空呈现出一片蔚蓝了
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