Rain occurs by the process of water cycle
the process of evaporatin is as
1. the water from water bodies evaporate due to the heat of the sun
2. the drops of water combine with dust particles in the atmosphere and clouds are formed
3. as the drops of water keeps on combining the clouds become heavy
4. when the clouds become heavy they are no longer able to float in air
5. then the drops of water fall as rain
How rain occurs Rainbows occur when sunlight passes through drops of water. This is why you see rainbows after rain or at fountains and waterfalls. Light moves at different velocities through air and through water. So when sunlight passes through water, it is dispersed. It is first refracted when it enters the droplet, reflected of the back of the drop, and then it is refracted again as it leaves. This refraction of the light into angles within the drop leads to it being visible, and the wavelength of the light is what depends its colour. After rain when sky is clear from the clouds and there is water everywhere. The sun shines on this water and reflects on the sky as rainbow.