Why the colour sequence in the secondary rainbow is reverse in order?

Answer 1

In a "primary rainbow", the arc shows red on the outer part, and violet on the inner side. This rainbow is caused by light being refracted while entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it.

In a double rainbow, a second arc is seen outside the primary arc, and has the order of its colours reversed, red facing toward the other one, in both rainbows. This second rainbow is caused by light reflecting twice inside water droplets.

Answer 2

The secondary rainbow occurs because the light undergoes two reflections inside the raindrop instead of one like in the primary rainbow. This extra reflection causes the light to exit the raindrop at a different angle, resulting in the colors being reversed compared to the primary rainbow.