I captured this beautiful phenomenon at dusk from my balcony. This perfectly visible double rainbow is one of the amazing displays of mathematics in nature. The primary rainbow is at an angle of 42◦ while the secondary rainbow at an angle of 51◦ together forming concentric semicircles. The two arches are due to double refraction of light from the sun through circular rain drops. A rainbow is actually a full circle, being on land one can only see the hemispherical arch as the remaining semicircle is blocked by the ground and horizon. If I could see this same rainbow from the pilot’s seat of an airborne plane, I would see it as a perfect circle!
S5ENA – European School Karlsruhe
14th February 2022