Question

Please explain how is secondary rainbow formed

Answer 1

Answer:

A secondary rainbow appears outside of a primary rainbow and develops when light entering a raindrop undergoes two internal reflections instead of just one (as is the case with a primary rainbow). The intensity of light is reduced even further by the second reflection, so secondary rainbows are not as bright as primary rainbows. Alternatively: fewer light rays go through the four-step sequence than the three-step sequence.

Answer 2

Secondary rainbows are formed by double internal reflection. Light is reflected twice from the inner surface of the raindrop before leaving the raindrop. ... They are reflected from the back surface of the raindrop, and refracted again as they exit the raindrop and return to our eyes