If you’ve ever found yourself wishing for the ability to read other people’s thoughts or the ability to see into your own heart,all you have to do is stare at the horizon directly at sunrise or sunset and look for a green flash of light.
Okay,maybe not. That may be an ancient myth made up by Jules Verne for his novel “The Green Ray.”
But the possibility of seeing a green light on the horizon is not fictional. The “green flash” may be rare,but it’s a very real phenomenon that can be seen as the sun pierces the horizon,either at sunrise or sunset.
These green flashes have dazzled onlookers and scientists alike and are a prized catch for photographers,but their cause is well-known.
How does it happen?
Our atmosphere acts like a prism that splits light into a visible spectrum and our atmospheric prism separates different strengths of colors from the sun.
When the sun is overhead,it is seen as an off-white or yellowish color because our atmosphere scatters the blue light into what we usually see as a blue sky. What's left over in the color spectrum is hued yellow.
But at sunset,the sun's rays are much more oblique to the eyes,so the light coming from the sun has much more atmosphere to go through and more colors are scattered away.
As the sun nears the horizon,those individual colors bend and bounce around in the atmosphere,but blue bends the most and red bends the least.
As the sun sets,the red light disappears first. The blue light gets scattered out by the atmosphere,so all that’s left reaching your eyes for a short time is the green light,creating that flash of green.
Other prisms are bike reflectors and sometimes glass,which can turn daylight into a small rainbow on the ground.
How to See the Green Flash
Unfortunately,if you’re looking for a bright green beam that leaps from the horizon into the sky as they show in Pirates of the Caribbean:At World’s End,you might miss the actual green flash,which stays much closer to the horizon.
Unless you’re lucky enough to see the illusive “green ray,” which looks much more like the omen that signals the return of a soul from the dead but only lasts a fraction of a second and has never been captured on camera.
But that doesn’t mean the regular green flash isn’t worth the effort to see!
First of all,never stare at the sun for a prolonged period. Let your camera do the hard work.
The best time to set up your camera is right before sunset because this is when the atmospheric optics are best for this effect.
It may be a little trickier at sunrise because you have to approximate where and when the sun will come up. There are a few online tools that can help with this,like SunCalc,which can give you a fairly specific time and direction (also known as the Azimuth) of sunrise.
The green flashes last only a moment or two. You should be in an area with a distant,flat and cloudless horizon to see through as much of the atmosphere as possible. Stable,sinking air commonly found in high-pressure areas can boost your chances of seeing a green flash.
Sometimes,if you're extraordinarily lucky,you might even see a blue flash like the one captured below.
Sara Tonks is a content meteorologist with www.weathernow24.com and has a bachelor’s and a master’s degree from Georgia Tech in Earth and Atmospheric Sciences along with a master’s degree from Unity Environmental University in Marine Science.
