Part 6/7:
As observations confirm, the colors in the secondary rainbow appear in reverse order compared to the primary. The refraction index of water causes this reversal. While conventional light spreads from red to violet in the primary arc, in the secondary arc, the internal reflections, combined with additional refraction through the air when exiting the droplet, result in violet being on the outer edge and red being on the inner edge.
This effect reflects the fundamental nature of how light behaves when passing through media of different densities. Understanding the refractive indices of different wavelengths of light provides insight into why we see the color reversal and what contributes to the formation of the secondary rainbow.