Sunlight outside the ionosphere is
unpolarized. But we never encounter it
unless we take a trip in the space
shuttle or one of those Russian Soyuz
rockets. Once the light hits the
ionosphere it becomes plane polarized to
a degree. That's the sunlight we
encounter down here on earth. The
atmosphere has an effect too but that is
quite unpredictable. Some sunlight
remains unpolarized. I don't know how
much, but you can easily find out. And
of course it will depend on where you
are in the world; in other words the
angle at which the light strikes the
ionosphere. Up in the North of Finland
its bound to be very different from down
here in the middle of the country.
My memory is not fresh on this subject
and I don't have time to go on but I'm
sure you will find all you need to know
on the web.
Don
[EMAIL PROTECTED] wrote:
OK, I see where the differences are.
Sunlight as such is unpolarized, but once reflected, refracted or scattered you
may have a partial separation of some polarization modes depending on the
direction. So, if you look at a blue sky through a window of polarizing
materials, and at the right angle from the sun, you can see the effect. If you
use polarizing sun glasses you dont need the polarized light from the sky.
If you really want to go into theory light particles, photons, have circular
polarization, so if you want linear polarized light you have to superimpose
them in pairs. .-)
DagT
fra: Don Williams <[EMAIL PROTECTED]>
If sunlight (skylight) were not
polarized, then polarizing filters would
have no effect and would not improve
your nice cloudy skies. The highest
percentage of polarized light from the
sky is to be found at about 90 degrees
to the sun's direction. To get the best
effect, have the sun to the right or
left of you when you start rotating your
filter to get that nice dark blue.
Sunlight that is reflected from a water,
or metallic or glass surface is further
polarized so that a polarizing filter
will (almost) completely eliminate the
reflection.
Don
[EMAIL PROTECTED] wrote:
No, sunlight is unpolarized, but as such it contains all polarizations and you
can extract anyone you want.
The reason why you can see the effect in some windows (and ice and a lot of
transparent hard plastic) is that the material acts as a polarizor. So if you
have the window of a polarizing material and you add another polarizer you can
get the effect. The reason why you get the colours is that the polarization is
wavelength dependent.
DagT
fra: Don Williams <[EMAIL PROTECTED]>
Sunlight is partially plane polarized.
Don
Peter Lacus wrote:
Hi Jostein,
To see the motif in the viewfinder just pop out as I turned the
polariser was an amazing experience.
Large version: 1000x668 pixels, 315 Kb
http://www.oksne.net/paw/sprekk1000.html
very nice, one time I did some shooting through the window of the
airplane and I've got similar rainbow effects. I still don't understand
how it works, though...
Bedo.
--
Dr E D F Williams
_______________________________
http://personal.inet.fi/cool/don.williams
See feature: The Cement Company from Hell
Updated: Print Gallery -- 16 11 2005
--
Dr E D F Williams
_______________________________
http://personal.inet.fi/cool/don.williams
See feature: The Cement Company from Hell
Updated: Print Gallery -- 16 11 2005
