A double rainbow occurs when sunlight is both refracted and internally reflected inside raindrops in the atmosphere. The primary rainbow is caused by light that is refracted into a raindrop, internally reflected once, and then refracted again as it exits the drop. The secondary rainbow, which appears outside the primary and has its colors reversed, is caused by light that undergoes two internal reflections inside the raindrop before exiting. The extra internal reflection causes the secondary rainbow to be fainter and broader than the primary. 🐶🐾🫡