How Rainbows Form: Light Refraction and Critical Angles Explained #2320854 (License: Personal Use)

The image illustrates the optical physics of rainbow formation, depicting how sunlight enters a spherical water droplet, refracts, reflects internally once (for the primary rainbow at ~138°) or twice (for the secondary at ~231°), and exits toward the observer. Critical angles-including 138°, 231°, 317°, and 400°-are labeled to clarify the geometry of dispersion and color separation across the spectrum. Red appears on the outer edge of the primary bow and inner edge of the secondary due to differing path lengths and angular deviations.

Used in educational science pages, meteorology resources, or physics tutorials explaining atmospheric optics; matches user intent to understand why rainbows appear at specific angles and how double rainbows form.