Why is there a Green Flash at Sunset?

The Elusive Green Flash Explained!
This beautiful physics phenomenon is able to be observed at both sunset and sunrise and is the result of some pretty simple astronomy and optics. In this video I explain the relatively recent history and physics surrounding the green flash, starting with light, the electromagnetic spectrum and refraction. We will see how this leads to the causes of rainbows and answers why the sky is blue before applying it to the light from the sun, our atmosphere and eventually understand the cause of the green flash! By the end you will understand how chromatic aberration, different wavelengths of light, Rayleigh scattering and refractive indices lead to seeing multiple different colour images of the sun at sunsets and sunrises which ultimately cause the green flash.
I will then give tips on how to see the green flash yourself. These involve the best places to observe, the times to look out for and advice on avoiding eye damage and after images.
Thumbnail Image Credit: Jim Grant, Twitter: @SDSCENICPHOTOS
0:00 - The "Dazzling Emerald Green Flash"
0:40 - Theory on Optics, Refraction and Electromagnetism Explained
1:44 - The Sun's Planck Black Body Spectrum and Radiation
2:32 - Earth's Atmosphere, Gravity and Optical Density
3:12 - Sunlight Chromatic Aberration and Rayleigh Scattering
4:49 - How to Observe the Green Flash Yourself (Tips)

[@OVAstronomy]

Let me know in the comments if you've ever seen the elusive green flash yourself!

[@JonathanBetzZall]

In the spring of 1978, the newspapers in San Francisco announced that conditions would be perfect for viewing the Green Flash from the westward facing beaches. We lucked out--the prediction proved correct and we got to see it! It was quite brief, a real flash, unlike other sunset phenomena which can stretch out for a few minutes.

[@jangaroo2011]

Superb explanation! Excellent tutorial on the Green Flash. I've seen the Green Flash twice at sunset during two vacations to Club Med Turks on the island of Providenciales in the country of Turks & Caicos. The biggest problem is actually being outside as the Green Flash will not announce its impending arrival. Second, you do need that clear ocean view towards the sunset. It was TRULY A MAGICAL MOMENT, or actually a minute or two, and then it's gone. Congrats to anyone else who's seen it too.

[@OVAstronomy]

Thank you so much! I will definitely be looking out for it next time I find myself on a beach holiday 🏖

[@mikenaye]

As a pilot, I’m always watching the sky. If the sun is setting, I’m watching for the green flash. I’ve seen it 15 times!

[@TheInvoice123]

Im color blind. Somebody needs to give me a time reference