Rainbows/Double Rainbows Explained - 47 ABC - Delmarva's Choice

Rainbows/Double Rainbows Explained

A rainbow may be visible after a rain shower or storm as a pretty present from Mother Nature.   A rainbow technically isn't a thing, it's an optical phenomenon.  Rainbows are best seen after a rain shower, with water droplets still in the air, the sun at your back and clear skies where the sun is.  The light enters the water droplet and because light travels slower in water, the light refracts (or bends).  The slower light then reflects on the inside of the droplet splitting the colors apart, forming the rainbow. The colors are separated by wavelength with violet moving the fastest and red the slowest.  This variation in wavelength allows for the violet light to travel faster and further, that's why it is at the bottom of the rainbow.   The color violet has a shorter wavelength and is not seen by the human eye easily, so that's why it appears paler.  The red light is much slower and is seen easily by the human eye and is visible at the top of the rainbow.

A single rainbow is seen when light has 1 reflection in a droplet, a double rainbow is seen when the light is reflected for a second time in the droplet.  With a rainbow, the light is refracted at 42°, but with the double rainbow the light for the second rainbow refracts off the droplet at 50°.  This is the reason why the second rainbow is above the initial rainbow.  The second rainbow also is dimmer as more light is released from the bow, and the second rainbow will also have reverse colors with red on the lower side and violet at the top.  This flip of colors occurs due to the 2nd reflection within the droplet.

(There isn't just one water droplet forming a rainbow it can be multiple millions of water droplets)

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