If the sun is shining and it is raining at the same time, a rainbow can appear in the sky. We are all happy and surprised to see the rainbow whenever we see it, as if we have seen it for the first time. But how is the rainbow formed? Let’s explain.
Did you know that white sunlight isn’t actually white? It consists of many colors. These colors are bundled in a sunbeam and give our brain the impression of white. The main colors that we humans can perceive are the so-called spectral colors. These are yellow, orange, red, green, violet and blue. But sunlight has even more colors that us humans cannot see like ultraviolet and infrared. But it is different with some animals as many birds, fish, reptiles and insects can perceive the ultraviolet color.
So what exactly happens when the sunlight meets the rain? When the bundled white sunlight hits a drop of water, it is deflected. This means that the sunlight is not transmitted in a straight line but it is deflected at an angle. This light is then reflected on the inner back of the water drop as if there were a mirror and directed back to the front. This is called reflection. It will direct the colors in the direction of your eye. If the light then emerges from the water drop, it is refracted a second time on the water drop wall. The angle from sunlight to the observer must be around 42 ° so that you can see the rainbow.
There are color gradients between the individual rainbow colors, which is why it is not possible to state an exact number of colors. In general, however, there are always six rainbow colors. Violet which is the innermost arch, blue, green, yellow, orange and red which is the outermost arch. These are the spectral colors of light that we talked about above. Each color is broken at a different angle, like red at 42 ° and blue at 40 °. That is why the white light beam is broken down into all its colors when it is refracted in the drop of water, which then appears in the rainbow. As you can see, red has a larger angle than blue. A larger angle means more refraction, so the red beam is deflected more than the blue one. Therefore, the red ray after the reflection is under the blue ray.
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Although all colors of sunlight are broken in every drop of water, only one color reaches your eye at a time. The water drops from which the red color arrives at you are at the top. The drops of water from which you get the blue color are at the bottom. The drops of water that the other colors send to you are arranged in between and this creates the order of the colors as you know them in the rainbow.
Almost never seen in summer
In the summer months the sun is so high around noon that the 42 ° angle can no longer be maintained and thus there is no rainbow. The higher the sun is on the horizon, the less you see of the rainbow. The rainbow is actually a circle, but you can only see it from great heights like from an airplane.
So it is sun, rain and the angle between the observer and the sun that determine whether we see a rainbow. Now, you know how the rainbow is formed and the aspects it depends upon. So next time when you see a rainbow, think about the science applied behind the creation of the colorful beauty.