Visitors to Bonaire often arrive on the island and hear about “the green flash.” It’s the Holy Grail of sightings when visiting Bonaire.
Exactly what is a green flash?
The green flash is an optical phenomenon that you can see just at sunset when looking westward from Bonaire’s leeward shoreline. When conditions are just right, a green flash can occur when the sun is setting with the majority below the horizon and just the barest edge of the sun is still visible. For a second or two, that upper rim of the sun might appear to turn green. Don’t blink, it’s a small, brief flash of the color green–the legendary green flash. It’s really quite exciting to see, especially if you’ve been watching for one.
What conditions are necessary to experience a green flash?
There are several conditions which must be “just right” before you can hope for a green flash on the western horizon.
A word of caution when viewing the green flash.
The science behind the green flash.
So many ask, exactly how does the green flash occur? As the sun moves down toward the horizon, the lower it gets the greater the thickness of atmosphere that you must view through. Those who SCUBA dive are already aware of refraction, the fact or phenomenon of light being deflected, or bent, when passing obliquely through the interface between one medium and another or through a medium of varying density. It causes items to appear closer and larger. Additionally, absorption of the color spectrum is the reason that colors are lost as one dives deeper in the water column. Colors are lost in the order of the visible white light color spectrum: red, orange, yellow, green, blue, indigo, violet. (Editor’s note–an easy way to remember this is the acronym, Roy G. Biv.)
In much the same manner, refraction is what occurs in a green flash. Water vapor in the earth’s atmosphere is absorbing the yellow and orange colors in white sunlight, and air molecules scatter the violet light. Only the red and blue-green light are left to travel directly to you. When nearing the horizon, the sun’s light is highly refracted. It’s almost as though there are two suns, and this is where the optical phenomenon occurs: a red sun and a blue-green sun–partially covering each other. The red sun is always closest to the horizon, so as it sets, your eyes see only the blue-green disk–the elusive green flash.
Keep your eyes turned westward at sunset to view Bonaire’s elusive green flash!
The moral of the story is that on your next Bonaire visit, take time out at sunset to sit quietly and watch the sun go down. After all, Bonaire sunsets are quite legendary. Not only is it a fitting way to end another day in paradise, but you might also just get lucky with perfect conditions, and experience the Holy Grail of sunsets–the green flash!