The Green Flash

• caused by refraction
• recall that short wavelengths (blue and green) refract more than longer wavelengths (red).
• hence, blue and green light should appear along the top of the sun.
• but, blue light is scattered away by Raleigh scattering, leaving green.... -> the green flash
• the green light is usually to faint to see.
• but is sometimes apparent momentarily, for a second or so.