When sunlight reflects twice within water droplets, light bends when it hits a drop, reflects off the drop, and then bends again as it leaves the drop. The second bow’s pattern shows the reverse of the first rainbow.
Image by Linda Tatreau
Sourced from Monolithic Commons
Tasi Dome Proves Trustworthy in Typhoon
CC BY-SA 4.0
Image by Linda Tatreau via Monolithic Dome Institute (CC BY-SA 4.0)