March 11, 2004
Observing from northern Chile during November and December of 2003, I enjoyed a number of magnificent sunsets from clear, high-altitude sites and was lucky enough to capture four green flashes from three different locations within a 3-week period. The upper left one was obtained at Las Campanas Observatory, the upper right one at Cerro Paranal, and the two bottom ones at La Silla Observatory. These photos demonstrate that you don't have to be on the water in order to detect the green flash. However, it's easier to observe the "flash" if the setting Sun appears more yellow in color rather than red. Dispersion in the atmosphere smears the setting Sun in such a way that a separate "image" appears for the red color, yellow color and the green color as well -- the rims of these "images" are stacked with the green rim on top and the red on the bottom. If conditions are right, once the red and yellow rims slip below the horizon, the uppermost green rim then sets with a discernable flash. See the links below for more information about the cause of the green flash.