#127Soap Bubble Film

A soap bubble seen head-on. A fake sphere normal gives a Fresnel term that thins the film toward the rim, crowding the interference orders into tight rainbow bands at the grazing edge while the crown stays broad and calm. Curl-noise flow migrates those bands around the surface, and the colour comes from real thin-film reflectance rebuilt on the Oklab ring, so the rainbow shifts as the film drifts. A soft specular sits at the centre and the very rim catches a bright grazing sheen.