The TRAVELER'S JOURNAL: January twenty-eighth, capturing the green flash.

The green flash is an occasional atmospheric phenomenon that for travelers can be so rare it borders on the mythical. That's because actually seeing one takes patience, determination and lots of luck. Here are thoughts on why, when and where to look.

When conditions are right, at either the first moment of sunrise or the last of sunset, a brilliant band of turquoise can shoot along the horizon. It happens when the sun's rays pass obliquely through a thick slab of atmosphere, which splits them into a spectrum of colors. Since the atmosphere scatters blue light, little of it reaches us. What gets through is a green that's usually too faint to be seen by human eyes.

But if the weather's just right, the sky clear and air hot, the atmosphere focuses the green. A careful observer in the right position, ideally at a high vantage point on a coast, may see a tight ribbon of intense color flash along the horizon, at the exact moment that the sun dips below the plane of the planet. Bingo. Normally, the green flash lasts only a second, and there are no instant replays. So to see it, an observer must be virtually staring at the horizon. Of course, if you happen to be near the North or South Pole, where the sun's elevation changes more slowly, the flash can linger. Admiral Byrd's South Pole expedition reported one that lasted half an hour.

In 1986, scientists at Cape Kennedy captured a green flash against the plume of a night missile launch. The photographic proof makes the green flash phenomenon slightly less elusive than the Loch Ness Monster.

Back to January 04 Main

Look through the list of fascinating places and off-beat features we’ve covered. Search text versions of past episodes and articles in our archives.