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Profile Does the Green Flash really exist? By Erin Blakemore January 2, 2006 San Diego--What's green, mysterious and the stuff of San Diego urban legend? Sorry, the answer is not The Incredible Hulk or the eyes of the barista you've been crushing on—it's the green flash, a gorgeous and elusive ocean phenomenon that you've probably looked for on one of San Diego's beaches. But what is this mysterious phenomenon, and why have you never seen it? What should you be looking for, anyway? Does it even exist? "Green flash" might sound like the name of a superhero, but it is actually an optical phenomenon that can be seen on the horizon at the moment before a sunrise or sunset. Observers note a quick, bright green ray of light that shoots forth from where the sun is rising or setting. Think they're just hallucinating? Well, not exactly—the explanation lies more in the realm of atmospheric chemistry than psychedelics. The flash phenomenon is due to light refraction in the atmosphere. Atmospheric layering at low altitudes creates a refraction of light (think of a prism which splits up the different wavenlengths of light) for a brief moment on the horizon, dispersing light and leaving only the green-colored light visible to the human eye. Think of the sun as a disk that has been cut into the seven colors of the spectrum. Under the proper atmospheric conditions, the eye suddenly sees the green layer of the setting sun for a brief second. Voila—a legend in action. If it's so simple to explain, then why is the green flash so legendary? Just look at a picture (find a great one here: http://antwrp.gsfc.nasa.gov/apod/ap040321.html)--the gentle layering of light created by the phenomenon is pure fantasy. Besides, who doesn't fancy an evening on the beach waiting for the sun to go down? Because of its dependence on very specific atmospheric conditions, the green flash is elusive to many viewers. Common mistakes include looking away at the crucial moment or letting impatience take over. And the wrong weather conditions, or even a stray cloud, are enough to dash a green flash seeker's ambitions. San Diegans are in luck—the altitude and climate of the beaches and bays is perfect for green flash viewing. Mission Bay sports a plaque explaining the phenomenon, and a Pacific Beach restaurant has even taken on its name. The lucky few who have viewed the green flash gain permanent bragging rights and tick a cool natural experience off of their list, so why not join their ranks and turn your next parking session into a science experiment? If you want to prove to yourself that the green flash does exist, the author suggests a warm blanket, a snuggly companion, a lawn chair and a discreet Thermos full of your beverage of choice. Scientists would add that a clear night increases the visibility factor, and timing is key—the flash only lasts for a few precious seconds, so no blinking allowed! -------------------- Erin M. Blakemore is a freelance writer and San Diego ex-patriot. You can read more about her writing--and exploits as a roller derby queen for the Denver Derby Dolls--at http://erinbee.xenius.org Suggested Vyuz reading... San Diego Dolls revive raucous roller derby | By Erin Blakemore Who's flagging pet postings on Craigslist? It's a mystery | By Larry Knowles The bare facts about Brazilian waxing | By Romina Cleary What pilots look for in airports, women | By Rob Potochnik A serial networker walks among us | By April Labine-Katko |
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