What Is Primary And Secondry Rainbow.

The primary rainbow forms between about 40° and 42° from the antisolar point. The light path involves refraction and a single reflection inside the water droplet. If the drops are large, 1 millimeter or more in diameter, red, green, and violet are bright but there is little blue. As the droplets get smaller, red weakens. In fine mist, all colors except violet may disappear. Even finer fog droplets, smaller than 0.05 mm, produce the white rainbow or fog bow. The secondary rainbow involves two reflections inside the falling droplets.
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