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What makes a rainbow?

With all this rain we’ve been having, it’s the season for rainbows. So what do you need to make a rainbow?
According to the McGraw-Hill Science and Technology Encyclopedia, “a rainbow is an optical effect of the sky formed by sunlight falling on the spherical droplets of water associated with a rain shower. The circular arc of colors in the rainbow is seen on the side of the sky away from the Sun. The bright, primary rainbow shows the spectrum of colors running from red, on the outside of the bow, to blue on the inside. Sometimes a fainter, secondary bow is seen outside the primary bow with the colors reversed from their order in the primary bow.”
In order for a rainbow to appear, the sun has to be low in the sky. The lower the sun, the higher the rainbow.  So the next time the sun is shining while the rain is still falling (maybe today!), check the sky for a rainbow. And if you find the pot of gold, please share it with the library.
Posted by Nancy, who saw the best rainbow ever one day while driving home from the library.