The reflection of 40 to 42 degrees is the strongest, which produces the rainbow we see. When this kind of reflection is caused, the sunlight enters the water drop, refracts once, then reflects on the back of the water drop, refracts again when leaving the water drop, and always refracts twice after one reflection.
Because water has dispersive effect on light, the refractive index of light with different wavelengths is different. The refractive index of red light is smaller than that of blue light, and the deflection angle of blue light is larger than that of red light. Because light is reflected in water droplets, the spectrum seen by the observer is reversed, with red light at the top and other colors at the bottom.
So the heights of rainbows and neon lights are different, and the hierarchical order of colors is just the opposite. Rainbow means that light is refracted twice and reflected once, while neon means that light is refracted twice and reflected twice.
Extended data
Rainbow legend: When the earth was born, Nana Bozhou lived in a house next to a waterfall. One day, he looked out of the window and found that all the flowers on his pasture were white. How monotonous it is, thought Nana. He decided to make some changes, so he came to the pasture with paints and brushes.
Nana Bozhou sat in the tall grass, put the paint bucket with red, orange, yellow, green, blue and purple pigments beside her, and then began to color the flowers on the pasture.
He painted violets dark blue and lilies of tiger skin orange with brown spots in the middle. Roses are painted red, pink and purple. Percy was painted in every color combination he could think of. Later, he painted the daffodils bright yellow. In the bright sunshine given by the sun god, Nana Bozhou hummed happily while working.
In the sky, two lovely little blue robins are playing games together. The first bluebird chased its friends in one direction. After crossing the pasture, they turned around again. The second bluebird chased the first one in the opposite direction. Zippy-Zip is the first bird to fly over the blue sky, and Zippy-zing is the second bird to chase Zippy-Zip under bright lights.
From time to time, Nanabo will put her hand on her eyes and look up at these two birds playing in the boundless sky. Then I went back and painted the middle of the white daisy yellow. In the air above him, two birds want to see how fast they can dive into the green Yuan Ye below.
The first bluebird flew again when it was about to touch the ground. When it flew over Naboo, its right wing touched the paint in the red paint jar. When the second bluebird swooped down, the left wing got the paint in the orange paint jar.
Nana Bozhou scolded the two birds, but they kept playing-diving into the grass where Nana Bozhou was sitting and then flying into the sky. In a short time, their feet and feathers were covered with various colors. Finally, Nana Bozhou stood up and waved her arms to drive away the two birds.
The two birds reluctantly left Nanabo and his paint pot and went to play elsewhere. They flew over the huge waterfall next to Nana Bozhou's house and started chasing each other again. Zippity-zip passed through the hazy fog generated by the waterfall, leaving a long red stripe in the air.
Zappity-zing chased his friend in the fog, leaving an orange stripe. Then the two birds turned around and flew back. This time, Zippity-zip left yellow stripes, while Zappity-zing left beautiful blue-purple stripes.
They fly around, leaving brighter and brighter colors. When the sun god sprinkled sunlight on these colors, the colors shone clearly through the fog generated by the waterfall.
Below them, Nana Bozhou happily watched these bright colors overflow from his pasture. A beautiful arch bridge has been formed in the sky above the waterfall. This arch bridge is composed of five colors: red, orange, yellow, green, blue and purple, and it shines with colorful light in the sky. Nana Bozhou smiled at two interesting bluebirds and said, "You have created a rainbow!" " "
Nanabo is very happy about this. He let the rainbow hang permanently above the waterfall. Under the sunshine, the rainbow flickered in the hazy fog. From then on, until today, whenever the sun shines in the rain or fog, it will form a beautiful rainbow. It is said that this rainbow is the reflection of that magical rainbow.
People's Network-How is the rainbow formed?
Baidu encyclopedia-rainbow