Green Flash Is A Rare Sight

Everyone knows the famous superhero “The Flash.” Faster than the speed of light, he’ll blitz by before you can even blink. Almost just as fast, but less commonly known, is the Green Flash. No, this isn’t one of the Flash’s comic book counterparts; it’s a natural phenomenon that you can catch with your naked eye. However, just like the Flash, you might miss it if you blink. 

The Green Flash is an optical phenomenon where the light just above the sun appears to turn green during a sunset, or more rarely, during a sunrise. It is easiest to see over the ocean, because there are fewer obstructions on the horizon’s edge. Other typical viewing spots can be found along prairies and deserts. Ideally, a flat horizon and a clear sky is the most welcoming background to observe these beautiful phenomena. 

To explain the green flash, we must first understand how the atmosphere works. The atmosphere acts as a big prism, separating light into its rainbow of colors. Remember, sunlight is a combination of all of the visible wavelengths of light, thus, when observing the sun from space, it will appear white. When sunlight enters into the atmosphere, it crashes into microscopic air particles and gets scattered around. The color of the sky depends on the angle of the lights entry. When the sun is rising and setting, longer wavelengths of light are scattered, making the sky appear red. As the sun makes its way overhead, shorter wavelengths are scattered and the sky will appear blue. 

The Green Flash is the result of this interaction between sunlight and the atmosphere. When the sun officially sets below the horizon, the top rim of the sun will still appear to be visible. This is due to the light being refracted, or bent, by the atmosphere before it enters the eye. This is also the best time to see the Green Flash as it may appear just above the top of the sun. 

Green Flashes aren’t always green. They can appear blue or even violet in the rarest occasions. However, green is the most common color associated with these events. The Green Flash can also come in a variety of shapes and sizes:

Green Flashes don’t have to be observed from the ground either. Many pilots have reported seeing flashes during their flight, so they can be observed from any altitude. They may also be observed with the setting of the Moon and other bright planets, especially Venus and Jupiter.
 

Usually when we see a red sky at night, we can take joy in knowing that favorable weather is on the way. But the grand finale to every red sky could be green. 

Image: This mosaic time-lapse shows the evolution of a green flash as the sun sets over the Pacific Ocean from San Francisco.  (Brocken Inaglory via Wikimedia commons)