Rainbow or Rainbow is an optical and meteorological phenomenon in the form of colorful light parallel to each other in the sky or other media. In the sky, the rainbow appears as a light arc with the tip pointing towards the horizon during light rain. Rainbow can also be seen around a raging waterfall.

Sunlight is a polychromatic light "composed of many colors". The white color of sunlight is actually a combination of various light with different wavelengths. The human eye is able to understand at least the seven colors contained in sunlight, which will see the rainbow: red, orange, yellow, green, blue, indigo, and purple.

The light wavelength is formed by parallel lines, each color to the color next to it. This recording is called the color spectrum. In the color spectrum, the red line is always on one side and blue and purple on the other, and this is determined by the difference in wavelength.

Rainbow is the only arc of a large spectrum of colors that occurs due to refraction of sunlight by drops. When sunlight passes through water droplets, it refracts like when it penetrates a glass prism and goes out into the rainbow color spectrum. So in water droplets, we have different colors in a row from one side to the other side of the water drop.

Some of this colored light is then reflected from the far side of the water droplet, back and out again from the water droplets. Light comes back from water droplets in a different direction, depends on the color. Rainbow colors are made in red above and purple on the bottom of the rainbow.

Rainbow is seen as an arc from the surface of the earth because of the limited viewing angle of the eye, if the point of view in the example of the height of an aircraft can be seen as a complete circular color spectrum. Rainbow can only be seen when it rains together with the sun shining, but from the side opposite the observer.