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Weather
in Southwest Florida
and "The Green Flash"
Southwest
Florida is projected to lead the nation over the next ten years in percentage
population, total personal income and new job growth. Phenomenal growth has sparked
an exciting new sense of energy and opportunity in a place that can only be described
as Paradise. Southwest
Florida's mean annual temperature is 75 degrees. Even though summer highs may
reach the 90's, the Gulf of Mexico dishes up delightful breezes, and brief afternoon
showers cool and wash the area.
| Climate
(in Fahrenheit degrees) | |
| Jan |
Feb |
Mar |
Apr |
May |
June |
July |
Aug |
Sept |
Oct |
Nov |
Dec |
| High | 77 |
76 | 82 |
86 | 88 |
90 | 91 |
92 | 91 |
87 | 83 |
78 | | Low |
53 | 52 |
57 | 61 |
66 | 70 |
72 | 72 |
72 | 66 |
60 | 55 |
| | | Rainfall
(in inches) | | |
1.9 | 2.0 |
2.3 | 1.7 |
4.5 | 7.8 |
8.0 | 8.5 |
9.2 | 4.0 |
1.2 | 1.4 |
|
| Gulf
Water Temperature (in Fahrenheit degrees) |
| | 66 |
66 | 71 |
77 | 82 |
86 | 87 |
87 | 86 |
81 | 73 |
68 |
Watch
For the Elusive 'Green Flash'
From the Naples Daily News
Gerry Johnson Twilight
is a time like no other.
Watching people on the beach watch the sun go
down can be as interesting as observing the colors and shapes on the horizon.
I know of no other natural phenomenon in Naples that produces applause and cheers
from throngs of onlookers. The observance of day's end seems almost instinctive,
a throwback to some tribal ritual of long ago. People
watch the sunsets for different reasons. Over the years viewers in Naples have
squinted into thousands of sunsets attempting to see the elusive "green flash,"
sometimes successfully. I am one of those who have been unsuccessful.
Until a few years ago I had always assumed that the flash was a local oddity,
something on the order of the "swamp gas" sightings over the Everglades.
However, it is actually a worldwide occurrence, even appearing in the dictionary
with the following definition: a momentary green appearance of the uppermost part
of the sun's disk that results from atmospheric refraction when the sun sinks
below or rises above the horizon.
The
December issue of the magazine Astronomy devotes an article to the green
flash and related optical illusions. Here is the gist of it. Sunlight
is bent as it travels through the Earth's atmosphere-with some colors being bent
more than others. Red is bent the least, followed in increasing order by orange,
yellow, green, blue and violet. As the light rays are bent, the colors become
separated. Sometimes when the light is bent in a certain way, it forms a rainbow.
Sometimes, under different circumstances, it creates images such as the green
flash. When
the sun is near the horizon, its light must pass through more of the atmosphere
before reaching our eyes, so the light rays are bent much more than when the sun
is high in the sky. The result is that, near the horizon, there is a stack of
overlapping images of the sun, with the red one at the bottom and the violet at
the top. We
normally don't see the blue or the violet images because they are scattered into
the atmosphere, causing the entire sky to be blue. Water vapor in the air usually
absorbs the orange and yellow rays. This leaves the faint green image and the
overpowering red image which penetrates a cloudy or dusty sky far better than
any other color. When
the red image sinks below the horizon an irregularly shaped patch of green remains
above for an instant, producing the flash. Some connoisseurs say that a yellow
or orange sun produces the best green flashes. Usually it is all over in a second
or so. In
order for the flash to be seen, the atmosphere must be extremely clear and the
horizon must be distant, well defined and flat. A view looking out over water
is best. Don't
stare at the sun too long before it sets or you may see a false green afterimage
on the retina of your eyes. You can create a bogus green flash by raising and
lowering your head behind an artificial horizon such as a concrete wall just before
sundown. Some
observers on boats have reported seeing the flash more than once during the same
sunset as they slowly rocked back and forth on heavy swells. Admiral Byrd once
observed the green color for 35 minutes as the sun rolled along the horizon in
the Antarctic. These and other tales are in the Handbook of Unusual Natural Phenomena
at the local public library. A classic description of the flash is in the January
1960 issue of Scientific American. Even,
if you don't manage to see it, it is great sport to watch for the green flash.
Sometimes the water looks so glassy and otherworldly just after the sun sets it
seems you could walk out and look over the edge to take another peek at the rim
of the sun where the green should have been. If you don't see it, there's always
tomorrow.
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