Whenever it rains and the weather is fine, if you are lucky, you can see an arched rainbow bridge in the sky. This beautiful colorful rainbow bridge aspires us, but have you ever wondered why the rainbow is arched and curved? After all, the light cannot be bent, but the rainbow is curved. Why?
Before we find out why the rainbow is curved, we must first understand the principle of rainbow formation.
A rainbow is a collection of rays projected into our eyes after a series of light movements such as refraction, reflection, and refraction of sunlight in small water droplets. Because there are a variety of light waves of different colors in the light, the reflection efficiency of these light waves is different, resulting in the rainbow that has finally appeared in our previous changes with different levels. Red light has the smallest angle of refraction, so red light is at the top; violet light has the largest angle of refraction, so purple light is at the bottom.
The refraction angle of red light is about 42 degrees, the refraction angle of blue-violet light is 40 degrees, and rainbows generally appear in this range. Using our glasses as the midpoint, and drawing a cone to the angle range where the rainbow appears, is the shape of the rainbow we can see. The reason why the rainbow we see on the ground is semi-circular and the rainbow we see in the air is circular is because the cone with the center point of our glasses is complete. When we were on the ground, a part of it was blocked by the land, and when we were in the sky, our vision was wide and it showed a complete circle.