How are these colourful meteorological phenomenons caused.
Ordinary rainbows happen when dampness in the air refracts daylight so that it is separated into its constituent colours.
The peculiarity happens when the Sun is situated behind you and daylight goes through the airborne water. These are often referred to as a primary rainbows.

The light refracts (twists) inside the beads and the white light is separated.
Each tone has a different angle, so depending on the point of refraction, a different shade of light will be reflected outwards; the consequence of this cycle is what we see when we see a rainbow.
Due to the angle at which the light is emitted determining the colour that will be visible, we know the range for red starts at 43 degrees and moves to violet at 40 degrees.
Each rainbow is joined by another, optional rainbow, be that as it may, it’s normally too faint to even see with the naked eye.
This twofold rainbow effect is expected to the proceeded reflection of light inside each water drop. Daylight is in reality reflected two times inside a drop: once to deliver the essential rainbow and a second time at the rear of the drop.
This second reflection rearranges the light yet goes through a similar refraction, so exits similarly as in the past – however topsy turvy.
This second reflection decreases the force of the daylight, however it likewise delivers a second modified rainbow, making a twofold circular segment of diverse light.
This is sometimes called an upside-down rainbow or secondary rainbow, as the inversion changes the angle at which the coloured light is emitted, ranging from violet at 54 degrees to red at 50.5 degrees.
The region between the two rainbows appears dark as no light reflected here is visible to the viewer and is commonly known as Alexander’s dark band.