Nature's optics and our understanding of light

Optical phenomena visible to everyone abundantly illustrate important

ideas in science and mathematics. The phenomena considered include

rainbows, sparkling reflections on water, green flashes, earthlight on the

moon, glories, daylight, crystals, and the squint moon. The concepts

include refraction, wave interference, numerical experimen,

asymptotics, Regge poles, polarization singularities, conical intersections,

and visual illusions.