The causes of rainbow formation

Rainbow is formed by the scattering and reflection of sunlight on spherical water droplets in the air. When sunlight enters the water drop, it will be incident at different angles at the same time and reflected at different angles in the water drop. 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.

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Historical significance of rainbow:

1. In China mythology, Nu Wa tried to make up the sky with five-color stones, and the rainbow was the colored light emitted by the five-color stones.

In Greek mythology, Iris is the messenger of heaven and earth.

3. In Irish folklore, goblins put their treasures at the end of the rainbow.

4. In Indian mythology, the rainbow is the bow of Indra (also translated as Indra), named Indradhanush. ..

5. In Norse mythology, the Rainbow Bridge (Bifr? St) Connect the domain of the gods "Asgard" (Asg? Rd) and the human settlement "Middle Earth" (Midg? Rd)。 That is, the traffic fortress between God and mankind can come and go through the Rainbow Bridge.

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