The Green Flash
Fable, Fiction and Fact
For centuries, mariners have shared ominous tales of magical bursts of green light directly above the sun as they watched it set on the water. But naysayers have brushed off their stories, claiming them to be a myth.
The stuff of real and Hollywood legend, its name traces back to the famous science fiction writer Jules Verne's 1882 novel, Le Rayon-Vert (The Green Ray), in which the heroine searches for the mysterious phenomenon.
While most pirate's lore can be chalked up to fantastical fiction, the green flash isn't. It is a real — albeit rare — scientific phenomenon. And, if in the right spot at the right time here in Costa Rica, you can see it … if you are very, very lucky.
What is the green flash?
A green flash is a phenomenon in which part of the sun appears to suddenly change to bright green for about one to three seconds. The brief flash of green light is seen most often at sunset, but has been known at sunrise. It is caused by the earth's atmosphere acting like a prism, separating sunlight into different colors. As the sun rises or dips below the horizon, the light bends and is dispersed into the atmosphere.
When the sun is high in the sky, light has a shorter distance to travel and the colors are not well separated. However, as the sun dips to the horizon, the light must travel farther through the atmosphere. As a result, the colors are more easily split up, just like a prism. When the conditions are exactly right, green wavelengths can reach our eyes, while the other colors are filtered out.
But it is very rare … and conditions need to be perfect.
How and where to see the green flash
Conditions must be almost perfect to see the flash. You must have a straight, unobstructed view of the sunset and the horizon, and there cannot be anything — including clouds — in the way.
With these conditions, your best chance to see the flash is looking west over the ocean at sunset, unobstructed by clouds. There are plenty of places to watch the sunset here in Costa Rica, but clouds often
ruin your chances. The best place to see one is on a Nicoya Peninsula beach, especially during the dry season, when the hot, dry air keeps the clouds to a minimum.
We always look for the flash when we travel to the ocean at sunset. We have tried hundreds of times to see it, to no avail.
Our luck changed on March 17, 2022, when we traveled to Santa
Teresa to visit with an old friend who was in Costa Rica for a conference. We decided to stop at Playa Santa Teresa for the sunset. I have taken sunset photos for decades, so I was enjoying this beautiful one when it happened. Luckily I had the camera on high-speed shooting. The green flash happened and we recorded it. A rare phenomenon and even rarer to capture it!
So the next time you stroll along the western beaches on a totally clear day near sunset, sit and wait for it. You may be treated to one of the rarer events on the planet. Enjoy hunting the green flash.