THE RAINBOW

السلام عليكم

 

A rainbow is not located at a specific distance from the observer, but comes from an optical illusion caused by any water droplets viewed from a certain angle relative to a light source. Thus, a rainbow is not an object and cannot be physically approached. 

Rainbows span a continuous spectrum of colours. Any distinct bands perceived are an artefact of human colour vision, and no banding of any type is seen in a black-and-white photo of a rainbow, only a smooth gradation of intensity to a maximum, then fading towards the other side.

Rainbows can be caused by many forms of airborne water. These include not only rain, but also mist, spray, and airborne dew.

The sky inside a primary rainbow is brighter than the sky outside of the bow. This is because each raindrop is a sphere and it scatters light over an entire circular disc in the sky. The radius of the disc depends on the wavelength of light, with red light being scattered over a larger angle than blue light. Over most of the disc, scattered light at all wavelengths overlaps, resulting in white light which brightens the sky. At the edge, the wavelength dependence of the scattering gives rise to the rainbow.

VARIATION OF RAINBOW :

Double rainbows

Full-circle rainbow

Twinned rainbow

Supernumerary rainbows

Reflected rainbow, reflection rainbow

Monochrome rainbow ( red rainbow )

Higher-order rainbows (can't see because of cloud)

Rainbows under moonlight ( usually in waterfall )

COLOUR OF RAINBOW :

Newton's first colours	Red		Yellow	Green	Blue		Violet
Newton's later colours	Red	Orange	Yellow	Green	Blue	Indigo	Violet
Modern colours	Red	Orange	Yellow	Green	Cyan	Blue	Violet