An arc-shaped luminous phenomenon that can be observed in the sky after the rain when one turns one's back to the sun and which presents all or part of the seven colours of the prism (violet, indigo, blue, green, yellow, orange, red).
A rainbow is a phenomenon that occurs especially when the sun is low on the horizon and the weather is cloudy or rainy. Rainbows can also appear on waterfalls or even on water sprayed with a spray bottle.
The common point? Water suspended in the air and, above all, white sunlight. The spectrum of light suddenly becomes perceptible and ranges from red to violet, including the main colours orange, yellow, green, blue and indigo.
The formation of a rainbow : How does this optical phenomenon occur? Light from the sun reflects off the water drops at an angle of about 40°. The water drops do not react quite like a mirror, otherwise the reflection of the sun itself would be observed, but rather like a prism that refracts the white light into a multicoloured spectrum.
The observer is therefore always situated between the sun, which he has behind him, and the top of the rainbow that is in front of him.