Why there is a rainbow after the rain in summer？
We can always see a rainbow after the rain in summer. Because there are a lot of small drops of water in the air after the rain. Light changes direction when passing through the drops at an angle, which is called refraction. If the drops are bigger, the rainbow will be easier to be seen. In winters, drops of water can seldom exist in cold air, and there is seldom a shower. So the rainbow usually cannot be seen in winters.
夏天的雨后，天空常常出現(xiàn)半圓形的彩虹，這是因?yàn)樵谟旰?，空氣中?huì)有大量的小水滴懸浮在空中，當(dāng)光線經(jīng)過(guò)這些水滴時(shí)，光就會(huì)出現(xiàn)折射現(xiàn)象，又因?yàn)樵诠獾恼凵溥^(guò)程中，橙黃綠藍(lán)靛紫等色光的折射角度不相同，就形成了我們所看到的彩虹。彩虹的明顯程度，取決于空氣中小水滴的大小，小水滴體積越大，形成的彩虹越鮮亮，小水滴體積越小，形成的彩虹就不明顯。一般冬天的氣溫較低，在空中不容易存在小水滴，下陣雨的機(jī)會(huì)也少，所以冬天一般不會(huì)有彩虹出現(xiàn)。