What shape is the rainbow? How is it formed?

Before answering what the shape of the rainbow is, we can review a picture called? The greatest scientific contribution of the western world in the middle ages? This scientific contribution is related to rainbows.

/kloc-at the beginning of the 0/4th century, a man named Dietrich? Feng? Freiberg's monk gathered a glass bottle full of water into the sun, with this? Big drops of water? Freiberg discovered the subtle reaction between light, water droplets and air, and solved the secret of rainbow formation.

Simply put, the rainbow itself is round, but because the lower part of the rainbow is not in our field of vision, the rainbow we usually see is semicircular. And the cause of rainbow formation can be used? A playful light in a small drop of water? To sum it up. From a physical point of view, sunlight is refracted at the interface between air and water droplets, and then reflected inside the water droplets, thus forming a rainbow.

Rainbow phenomenon usually occurs after thunderstorms in summer, from overcast clouds and downpours to clouds blocking the sunrise, when rainbows will appear in the eastern sky. In addition, when the sun rises in the morning, you will see a rainbow when you look at the western sky that has already rained. So rain and sunshine are the most basic weather conditions for rainbows. Small raindrops that can present a rainbow should not be too far away from the observer, usually 1 to 2 kilometers is the best. Although we often think that the rainbow looks far and big, it is actually an illusion.

There is a popular folklore in Europe that a pot of gold can be found at the end of the rainbow, which is obviously a beautiful sight in people's imagination. Because the rainbow is invisible, it is just a scene where light reflects, decomposes and projects inside the water droplets. Sunlight is a random combination of light with different wavelengths. When it enters the water drop from the atmosphere, it has a short stay and interruption, and some of it is emitted from the water drop and quickly shoots into the distance.

All kinds of light mixed and staggered in sunlight are refracted and decomposed by water to varying degrees, and finally refracted from water droplets to the outside at different angles. Among these lights, blue light is more easily blocked by water droplets than red light. We can imagine a scene in which blue light propagates slowly in water droplets. Because of the short wave length, it will be deeply surrounded by dense water molecules, so the speed of blue light will be slightly slower than that of red light.

We often say that the rainbow has seven colors: red, orange, yellow, green, blue and purple. In fact, the colors of the rainbow from the outside to the inside are red, orange, yellow, green, blue, cyan and purple, with purple inside and red outside.

The lower the setting sun in the west, the higher the rainbow in the eastern sky will rise, and the bigger the arch of the rainbow will be. In other words, when sunrise and sunset are about to sink into the horizon, the rainbow you can see is the biggest.

At noon, we can hardly see the rainbow. In our field of vision, if the angle between the sun and the ground is greater than 42 degrees, we can't see the rainbow, but that doesn't mean that the rainbow doesn't exist at all. If we take off in a hot air balloon, we will find a huge, closed rainbow, and the shadow of the hot air balloon is right in the center of rainbow circle.

Besides rainbows formed by weather factors, we can also see rainbows when fountains, waterfalls and even sprinklers spray water. The reason for the formation of rainbow has not changed, but it is still a physical phenomenon among light, water droplets and air, but the source of water has changed.