What causes the strange green flash at sunset and sunrise on Earth?

There are very special cases, when the sky is very clear and exceptionally transparent, that a green flash can be glimpsed just as the very topmost part of the sun is rising or setting.

15 Spectacular Natural Phenomena in The Sky

Green Flash - Information

London-Inspired Tennis Gear from All Your Favorite Brands🤍 - Tennis Point

Green Sunsets Are 100% Real

Rayleigh scattering: a phenomenon that affects the sky., Misbahul Islam posted on the topic

Flashing the sun and breeze

Sea Science: There's a reason that green flash at sunset is so rare

Green Flashes – WeatherTogether

No sun, no life on earth

Just saw this in dandadan : r/BLAME

When the California sun turns green, by Mike McPhate

Green Flash Hawaii: How to See It For Yourself

Telos Discovery Space Center

Catching the elusive 'green flash' American Association for the Advancement of Science (AAAS)