rainbow 的形成作文

The rainbow is a very common phenomenon of physical optics. Usually when we will appear in the sunshine after the rain to see the sky above, colorfulspectrum, will be the formation of vaulted curved shapes, very bright colors.You know why the rainbow is formed? How is the rainbow formed?
In fact, as long as the water droplets in the air, and the sun is behind the observer at a low angle radiation, may produce the rainbow phenomenon can be observed. The rainbow is because sunlight nearly round air droplets,resulting in dispersion and reflection light into. The sunlight will also drop under different incident angle, within the water droplets is to reflect the different angle. With the reflection between 40 to 42 degree is the most intense, the formation of people may see the rainbow. The rainbow after the rain in the afternoon appears most often, just turn when the weather is fine. When the air in less dust and full of small water droplets, the sky side because there are still clouds and dark. And the observer has no head or behind the cloud occlusions visible sunlight, it will beeasier to be seen rainbow.
The general appearance of the rainbow is closely related with the weather,people from the rainbow appears in the sky position can be presumed that there will be sunny or rainy days. If the rainbow appears in the eastern, the local will not easily rain, while western rainbow, it will have a great possibility to rain local.