Who first discovered the rainbow?
It is quite difficult to say exactly who exactly first defined what a rainbow really is. This unique natural phenomenon was known to our ancestors. For example, in the symbolism of many peoples, it was customary to identify a rainbow with a huge snake that drank the seas, rivers and lakes. The semicircular shape of the rainbow made people think of a ring that covered the entire earth. In China, the rainbow was considered to be a heavenly dragon, which was a kind of sign of the union of the two principles of yin and yang. In ancient Rome, for example, the rainbow was considered the bow of Indra (the god of thunder). And in Hinduism, the rainbow was called the highest yogic state, which can be achieved in the realm of samsara. Among the Indians, the rainbow was considered a good deity.
But that’s all in the distant past. But in 1596, for the first time, the philosopher and writer from France, Rene Descartes, began to write about the rainbow. It was he who dealt with this question systematically in his famous work entitled Discourse on Method in 1967. Descartes was able to make a conjectural calculation of the paths along which the rays of light passed at different points of the glass globe with water. Thus, he was able to determine the angles of refraction. However, Descartes only made a hypothetical explanation, but the Dutch astronomer and mathematician Willebrord Snell discovered the mathematical law of light refraction 16 years before Cartesian’s dissertation on this issue was completed. However, the scientist could not publish his work. In 1626 he died.
About the rainbow will be more in this video.
Scientific rationale for the appearance of a rainbow
The rainbow is considered to be one of the most beautiful natural phenomena. People have been interested in how and where this amazing phenomenon comes from since time immemorial. Many even associated the appearance of the rainbow with many beliefs and legends, people managed to compare the rainbow with a heavenly bridge and classify it as magic. But meanwhile, the rainbow, as a natural phenomenon, can be explained from a scientific point of view. This atmospheric optical phenomenon is usually observed when the Sun begins to illuminate many water droplets during rain or fog, and also after rain. That is, a rainbow appears in the sky, as a result of the refraction of sunlight in drops of water. A rainbow can also appear in reflected sunlight from the water surface of reservoirs, waterfalls and sea bays. Such a rainbow looks as impressive as possible.
Why are there seven colors in the rainbow?
A long time ago, scientists were able to prove the fact that the rainbow has a continuous multi-color spectrum. However, it is customary to distinguish seven primary colors in it. Interestingly, it was Isaac Newton who first used the concept of "spectrum" when describing his optical experiments. During his experiments, the scientist was able to observe the reflection of light, due to the fact that a beam of light fell on the surface of a glass prism at an angle to the surface. Moreover, part of the light incident at an angle passed through the glass, forming multi-colored stripes. Isaac Newton divided light into seven colors, but he noted in his scientific papers that only five were originally discovered by him. The first colors discovered were red, yellow, green, blue and purple. Blue and orange were added to him only later. As for the number seven, then it was chosen by scientists also for a reason. The seven was chosen from the belief that there is a certain inexplicable connection between colors, musical notes and objects of the solar system and the days of the week. But, remarkably, this theory was not equally well received by all. For example, the same Americans and the French believe that the rainbow has six colors. And the Japanese have no green at all in the spectrum. And this is largely due to the fact that the Japanese language does not have such a color as green. And the Japanese have no green at all in the spectrum. And this is largely due to the fact that the Japanese language does not have such a color as green. And the Japanese have no green at all in the spectrum. And this is largely due to the fact that the Japanese language does not have such a color as green.
The width and brightness of the rainbow: what do they depend on?
According to calculations using the formulas of the diffraction theory, which were performed for drops of different sizes, the width of the rainbow, its presence, the location and brightness of the colors, as well as the position of the arcs themselves depend directly on the size of the raindrops. So, for droplets with a radius of 0.5 to 1 mm, the outer layer of the main rainbow will be bright dark red, followed by light red and all other shades of the rainbow. Violet and green colors will appear especially bright in this case. With a raindrop radius of 0.25 mm, the red edge of the rainbow will appear less intense. The rest of the colors will have the same intensity, but some purple arcs will change to green. With a raindrop radius of 0.1 and 0.15 mm, there will be no red color in the rainbow. The outer layer of the rainbow will be orange, and additional arcs will be increasingly yellow. And between them and the main rainbow and the first additional, characteristic gaps will appear. Thus, it turns out that it is by the color of the rainbow that one can determine the size of raindrops. The more raindrops, the brighter the rainbow.
Double rainbow: why does it appear?
Sometimes two rainbows may appear in the sky instead of one. Behind an ordinary rainbow, a second one can be clearly seen, the color of which will be less intense. In some cases, the second rainbow may be subtle and almost invisible. In the second rainbow, as a rule, all colors are inverted. That is, it first comes with a purple hue. Why is this happening? And why does the second rainbow appear? The fact is that the appearance of the second rainbow is explained by the repeated reflection of the sun’s rays inside the raindrops.