Why does a rainbow form usually after it has rained?

Question

Why does a rainbow form usually after it has rained?

Answer 1

Rainbow is formed when the water droplets act as prism and split the sunlight into its seven colours by refraction and total internal reflection so as to reach the observer's eye.However the extent of resolution(dispersion) of the seven colours in the droplet depends upon the extent of the (path) length the rays cover in the droplet.In normal clouds,the droplets are too small to cause sufficient resolution of the colours and to enable total internal reflection and hence rainbow is invisible with dry clouds.

On a rainy day,the droplets are big enough to cause the resolution and total internal reflection of the colours to enable us to see the rainbow.Further they are numerous and closer and at an appropriate viewing angle to cause the phenomenon.

Answer 2

a rainbow is a spectrum of light that is because of the refraction of white light through a raindrop of (clear) water

therefore a rainbow usually happens at the meeting between sunshine and rain

Answer 3

rainbows form...as it rains.they become visible from a distance.   the result is light refracting

Answer 4

water refracted in droplets still in air far away

Answer 5

Waters droplets reflecting sunlight. It works like a prism.  Read below.

Answer 6

AFTER IT HAS RAINED, THE CONTENT OF WATER   VAPOUR   RISES   IN   THE   ATMOSPHERE  AROUND US.  DUE TO IT , THE  

AMOUNT OF WATER  DROPLETS INCREASE .SINCE THESE   DROPLETS  ACT AS  PRISM,  WHICH IS MAINLY RESPONSIBLE   FOR  APPEARANCE   OF  RAINBOW      (THE  SUNLIGHT  AFTER  PASSING  THROUGH  IT  ,  SCATTERS  INTO  ITS  COMPONENT  COLOURS  FORMING  A  SEVEN   COLOURED  RAINBOW)       .THE  SUNLIGHT  IS  SCATTERED  MORE  CLEARLY  AND HENCE  WE  SEE  A  RAINBOW  GENERALY  AFTER  RAINFALL.

Answer 7

Because light reflects from water droplets :]