Green glow

A green glow is a rare optical phenomenon that usually occurs at sunrise or sunset (or, more rarely, full moon), when a small green spot is visible for a short time above the sun or moon, or next to them. It is most easily visible in photographs.

They are observed from any altitude. They are most easily seen on clear horizons, such as over the ocean, but also possible over mountains and clouds.

The reason for its appearance is based on the refraction of light. As in a prism in the atmosphere, light moves more slowly on the lower horizon due to air density, so sunlight follows slightly curved paths in the same direction as the curvature of the earth.

The higher light frequencies (green, blue) bend more than the lower frequencies (orange, red), so that the blue and green rays become more visible on the solar surface, and the warmer tones obstruct. Green glows are enhanced by atmospheric inversion, which increases the density and consequently the luminous refraction.

We can also see a blue glow, but blue is more scattered in the human line of sight, and usually turns green.

With a slight magnification, green sparkles are seen at the top edge of the sun disk on clearer afternoons, however, different types appear at different times. Most last 1 or 2 seconds, but some last up to 15 seconds.