Scientific explanation

The light is first refracted as it enters the surface of the raindrop,reflected of the back of the drop,and again refracted as it leaves the drop. The overall effect is that the incoming light is reflected back over a wide range of angles, with the most intense light at an angle of 40-42 degrees. The angle is independant on the size of the drop, but does not depend on its rafractive index. Seawater has higher refractive index than rain water, so the radius of a 'rainbow' in sea spray is smaller than a true rainbow. This is visible to the nacked eye by a misalignment of these bows. The amount by which light is refracted depends upon its wavelenght,and hence its colour. Blue light is refracted at a greater angle than red light, but because the area of the back of the droplet has a focal point inside the droplet , the spectrum crosses itself, and therefore the red light appears higher in the sky, and forms the outer colour of the rainbow.

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