What is a rainbow (graphic)

The definition of rainbow Rainbow, also called rainbow over the sky, is an optical phenomenon in meteorology. When the sun shines on the water droplets in the air, the light is refracted and reflected, forming an arched color spectrum in the sky, which is a common phenomenon after rain. Curved, usually semicircular, with rich colors. As an optical phenomenon, special rainbows are not always single. There are also some special rainbows, such as double rainbows and late rainbows. Double rainbow is a special phenomenon formed after two reflections in water droplets. A concentric rainbow with a slightly larger diameter and reversed color appears on the periphery of the original rainbow. The inner rainbow is called the main rainbow and the outer rainbow is called the auxiliary rainbow, which looks like a hair band. Sunset is a rare phenomenon, which may appear in the night with strong moonlight. Because it is difficult for human vision to distinguish colors in low light at night, the night rainbow looks as if it is all white. The rainbow is not a semicircle as people imagine, but a complete circle. The center of the rainbow is the midpoint of the vertical line between the sun and the earth. The rainbow that people see is only a part of the rainbow, and the rest is below the horizon, so people can't see it. This can also explain why some rainbows are short, while others are complete semicircles. When the rainbow presents a complete semicircle, the sun is just on the horizon, and the center of the rainbow is just on the horizon in front of the observer. When the sun is high in the sky and the center of the rainbow is below the horizon, people can only see a few rainbows.