Flashy phenomenon

A green flash is just one of many refractory displays seen over the Pacific Ocean

Each evening, visitors and residents alike pause to gaze westward to enjoy the breathtaking sunsets that are one of coastal Southern California's most stunning features. A lucky few--those who know what to look for--are sometimes afforded the additional pleasure of catching sight of a green flash.

"A green flash is the appearance of a bright green color on the upper part of the sun's disk," said Andrew Young, Ph.D., an adjunct professor of astronomy at San Diego State University and the local go-to guy for information about this rare phenomenon. "It can be the last bit as the sun sets or the first bit as the sun rises."

Green flashes, which also manifest as rays, glows and dots, are the result of atmospheric dispersion: refraction of the sun's light wavelengths. The momentary flash typically ranges in color from pale green to vibrant emerald but can also appear blue, blue-green or violet.

While green flashes occur year-round and can be seen around the world, there are certain conditions that increase the odds of seeing one.

Being situated on the ocean is advantageous for two reasons. The first is that because the ocean is lower than a person's line of vision, it provides the strip of sky necessary to view the green flash. The second is that the disparate temperature between air and ocean produces the thermal structure that magnifies the visual presentation.

"This is a good place to look for green flashes," Young said. "La Jolla is where I have driven many times to photograph green flashes. Either up at Torrey Pines or down on the beach; any place in between is a good place to look for green flashes."

Because green flashes occur at the final moment the sun drops below or rises from the horizon, an unobstructed view is mandatory. Young also suggested using a low-power telescope or binoculars to enhance the mirage effect.

There is also a seasonal consideration to catching sight of green flashes, Young noted. If the water is colder than the air, such as during Santa Ana winds, get up to a cliff in order to look down on the thermal inversions. When the water is warmer than the air, beach level is prime viewing.

Photographing green flashes is no easy feat, as professional photographer Oscar Medina can attest. It took the San Diego photographer more than nine years to capture his first flash. He has since documented the phenomenon numerous times, using special filters and techniques. The first bit of advice he has for people viewing and photographing any sun-related event is to protect their vision.

"Do not look at the sun," Medina cautioned.

For those willing to take on the challenge, photographer, artist and printer Jim Respess of Green Flash Photography in Pacific Beach shared what has worked for him: use a tripod; shoot three to five stops down from normal; set a small aperture and shoot a series of shots.

"It's easy to see with your eye when you know what to look at," Respess said, "but it's not so easy to catch with a camera because your camera has a limited availability to catch the range of light."

Young said there is something fascinating about green flashes. Perhaps it is their rarity or simply the sheer drama of how the brilliant green flashes against the red and yellow and purple hues of sunset.

"It's kind of an uncommon thing, so not very many people have seen them," Young said. "If you get to see a green flash, you can consider yourself among the lucky few."

Dazzled by this elusive display since the 1950s, Young has assembled his considerable knowledge into a Web site (

http://mintaka.sdsu.edu/GF/

) and suggested that novice green flash chasers start there.

"It helps a great deal to know what to look for," Young said. "Just go and look a lot. Make it a regular practice to look at the sun when it gets down close to the water. Now and then, you'll get to see a green flash."

Birch Aquarium at Scripps shines with its own Green Flash

Held on the aquarium's Preuss Tide Pool Plaza from which green flashes are often seen, the Green Flash Concert series features a different musical performance every third Wednesday of the month through September. The lineup includes Shawn Mullins (June 17), Steve Poltz (July 15), Jack Tempchin (Aug. 19) and Venice (Sept. 16).

This year, Birch Aquarium at Scripps will be holding a Green Flash Concert photo contest. Winning images will be displayed, and the photographer will receive two free tickets.

The concerts are from 6 to 9 p.m., and ticket prices vary. Guests must be age 21 and older.

For information or advanced reservations, call (858) 534-4109.

Click

here

for more information on the series.

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