十万个为什么·科学启蒙30篇（3）
6 / 30
正在校验访问权限...
How Does a Rainbow Form?
彩虹是怎么出现的
-
A rainbow appears when sunlight enters a raindrop, bends, reflects off the back, and bends again while exiting.
-
Each color of light bends by a slightly different amount, separating white light into its full spectrum.
-
Red light bends the least and exits at about 42 degrees, while violet bends the most at 40 degrees.
-
Your eyes see red higher in the arc and violet lower because of these precise exit angles.
-
You must stand with your back to the Sun and face falling rain to see a rainbow at all.
-
The center of the rainbow’s circle lies directly opposite the Sun from your viewpoint.
-
Double rainbows happen when light reflects twice inside the drop, reversing the color order in the outer bow.
-
Rainbows are not physical objects—they exist only where light, raindrops, and your eyes align perfectly.
-
Fogbows look white because tiny fog droplets scatter light too broadly to separate colors clearly.
-
At sunrise or sunset, the Sun’s low angle can make rainbows appear fuller and more vivid.