After it rains, we put away our umbrellas. Then we may see rainbows in the sky above us. The conditions need to be just right to see a rainbow. We need some water drops in the air, like rain, fog or clouds, and we need the sun to be behind us and low to the ground, which often happens in the autumn, because a rainbow is created by light passing through water drops. As the name suggests, rainbows are supposed to be the shape of a bow. Neither the sun nor the water drops are the same every time, so each rainbow is unique. Rainbows could also look like some colourful smoke.
雨停之后，我们收起雨伞。这时，在头顶上方的天空中，我们可能会看到彩虹。要看到彩虹，必须有恰到好处的条件。我们需要空气中有一些水滴，比如雨、雾或云，同时需要太阳位于我们身后且位置较低，这种情况在秋季经常出现，因为彩虹是由光线穿过水滴形成的。顾名思义，彩虹应该呈弓形。每次的太阳和水滴都不会是一模一样的，所以每条彩虹都是独一无二的。彩虹也可能看起来像一些彩色的烟雾。
The light that comes from the sun seems white to us. But the white light is actually a mix of different colours. When the light goes through a raindrop, these colours can separate out. Raindrops look like little balls. When light hits one of these little balls, it changes direction. We call this “refraction”. Lights of different wavelengths are refracted differently, so they are separated out into different colours.
我们看到的来自太阳的光似乎是白色的。但这种白光实际上是不同颜色混合起来形成的。当光穿过雨滴时，这些颜色就会分离出来。雨滴看起来像一个个小球。当光线射到其中一个小球上时，它会改变方向。我们称之为“折射”。不同波长的光折射程度不同，因此会被分离成不同的颜色。
In a rainbow, there are seven colours arranged in a row: red, orange, yellow, green, blue, indigo and violet, while colours like brown and pink are not usually seen. And we would never see black and white in a rainbow. Black is what we see when there's no light, while white is a mix of all the colours together.
在彩虹中，有七种颜色依次排列：红、橙、黄、绿、蓝、靛、紫，而像棕色和粉色等颜色通常是看不到的。我们永远不会在彩虹中看到黑色和白色。黑色是在没有光的情况下我们看到的颜色，而白色则是所有颜色的混合。
The science of rainbows is fascinating. Even on a busy weekday, we should look up to the sky. It's an easy way to appreciate the beauty of nature.
彩虹的科学原理非常迷人。即使在忙碌的工作日，我们也应该抬头看看天空。这是欣赏自然之美的一种简单方式。