The colours of the rainbow (spectrum): red, orange, yellow, green, blue, and purple Transitions from one colour to another, several hues.

   In white solar light, all hues of the colours are hidden - red, orange, but they are also iridescent: red and orange, orange and red etc. If the light passes through the transparent prism (e.g. a raindrop), it breaks up into the colours of the rainbow.
   Therefore, we see the rainbow when there is the sun and the rain at the same time.