![[puerto sunset]](images/covershot41.jpeg "puerto sunset")
As if the perfect Puerto sunset were not reward enough, the waning hours of
daylight are when many local bars & restaurants seek to enhance these magic
moments - - and entice your patronage - - with the venerable tradition of
Happy Hour. More for less; so don't worry, be happy!
FOR DECADES, Topic Number One among Puerto's sunset aficionados has been the elusive Green Flash. Now cynic, that I am, my theory was that these alcohol and substance infused individuals, after gazing intently at that brilliant red orb as it slipped gently into the ocean, were experiencing an optical illusion, as a negative image - - the color green - - was emblazoned onto the retina.
Not so, says my science consultant, the reclusive Dr. K. as he now explains:
![[green flash]](images/greenflash.jpeg "green flash")
When the Sun sets, sometimes the last bit of light from the top of the solar disc itself is an
emerald green colour. This phenomenon is known as the "green flash" or "green ray." It is not an
optical illusion, nor does it fill the sky with green light. Usually, the effect is very subtle,
but occasionally the result is intense.
The green flash is quite common and will be visible any time the Sun is rising or setting on a
clear, unobstructed, and low horizon. From Puerto, that means the
horizon must
be exceptionally clear at sunset with no apparent clouds or haze. The flash typically lasts one or
two seconds. It helps to look away until the last possible instant to avoid over saturating your
vision.
![[spectrum]](images/spectrum.jpeg "spectrum")
The explanation for the green flash involves refraction, scattering, and
absorption.
![[green flash]](images/greenflash-2.jpeg "green flash")
First, the most important of these processes is refraction. Sunlight is bent by the earth's
atmosphere resulting in our image of the Sun on the horizon appearing roughly a solar diameter
*above* its actual position. That is, if there was no atmosphere, the solar disc would already have
disappeared below the horizon.
Refracting white light, combining all the colours, through any clear substance such as water, glass, or air, causes the different light wavelengths to be refracted at different angles, similar to a spectrum from a prism or rainbow.
Blue light with shortest wavelengths is refracted the most. Red light with longest wavelengths is refracted, or bent, the least. Thus, the Sun's disc in red light would appear to be lower in the sky than the solar disc in blue light. The blue disc is actually the last to set after green.
The blue light is Rayleigh scattered away. The size of air's gas atoms causes blue wavelength light to be scattered more than the other colours. This effect makes the sky blue.
Air has a weak yellow optical absorption band. When the Sun is overhead, this absorption isn't significant, but once near the horizon, the solar light travels through approximately 38 times more air, so even a weak absorption becomes substantial. A setting Sun loses most its bright yellow colour.
The beaches, the points, the hills, each of us has a favorite spot to absorb
this precious daily occurrence, delivered free of charge, but with the power
to center us, to make us believe that all is well with this world and things
are as they should be.
(I'll tell you mine if you'll tell me yours: e-mail
me at elsolinpuerto@gmail.com and in one of the upcoming issues, when, we trust,
our glorious sunsets will continue, I'll publish your sunset sites, your
sunset poetry, photos, mantra or musings.)
But on those evenings when you are of a convivial mood and choose to pass this time with fellow humans, and to partake of the discounted hospitality of those who wish to contribute to your happiness, may we offer these suggestions:
![[zicatela sunset]](images/zicatela_sunset.jpeg "zicatela sunset")
![[marinero sunset]](images/marinero_sunset.jpeg "marinero sunset")