By Marcy Shortuse • Photos by Boots Tolsdorf and provided
Most nights at sunset in Boca Grande
you’ll fi nd a gathering of people
who have made it a tradition to see
the day out with a toast, and maybe even
a sigh of appreciation. Our sunsets can be
quite spectacular over the Gulf of Mexico,
and if you’re lucky you might even get a rare
glimpse of the “green fl ash,” sometimes
known as “Neptune’s wink.”
Many have heard of it, less believe it is real.
It is, though, as many of our sunset groupies
(and science) can attest, usually seen as a
band or vertical ray of bright green light just
above the setting sun. To see it you need a
clear, fl at horizon and a haze-free sky. That
last part can be tricky, as African dust is often
what makes our sunsets so amazing … albeit
hazy.
The last rays of sunlight bending in the
atmosphere cause the green fl ash. This is
called “refracting.” At sunset the light has the
most atmosphere to be refracted by, and the
sun is surrounded by shadows of different
colors that have been separated out. The atmosphere
absorbs many of the colors – such
as red, orange and yellow – and blue and
purple shadows are scattered. That leaves
the color green.
Sometimes, on super-clear evenings – you
might also see a “blue fl ash.” This is because
the air is clear enough to allow those purple
and blue colors to make it through the
atmosphere.
It takes more than normal refraction to
create a green fl ash, though. According to
the American Association for the Advancement
80 GASPARILLA MAGAZINE November/December 2019
of Science, there are four categories of
green fl ashes: Inferior mirage; mock mirage;
subduct fl ash; and green ray. Almost all of
the green fl ashes you see fall within the fi rst
two categories. Inferior mirages are oval and
fl at, and occur close to sea level when the
surface of the water is warmer than the air.
Mock mirages occur higher up in the sky and
when surface water conditions are colder
than the air. They look like thin slices or strips
in the setting sun.
The lesser well-known subduct fl ash occurs
in an hourglass shape due to atmospheric inversion.
That happens when a layer of warm
air traps cooler air and moisture close to the
ground. A subduct fl ash can sometimes be
seen for up to 15 seconds.