| Topic: |
Science > Physics |
| User: |
"Jim" |
| Date: |
01 May 2007 10:34:22 AM |
| Object: |
Rayleigh scattering coefficients |
I am looking for measured rayleigh scattering coefficients for the
visible spectrum. Up to now I was unable to find any tabulated data
published online. I hope someone can point out a useful site.
Best regards
Timm
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| User: "galathaea" |
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| Title: Re: Rayleigh scattering coefficients |
01 May 2007 11:35:23 AM |
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On May 1, 8:34 am, Jim <timm.von.puttka...@googlemail.com> wrote:
I am looking for measured rayleigh scattering coefficients for the
visible spectrum. Up to now I was unable to find any tabulated data
published online. I hope someone can point out a useful site.
what medium?
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
galathaea: prankster, fablist, magician, liar
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| User: "Jim" |
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| Title: Re: Rayleigh scattering coefficients |
01 May 2007 12:03:33 PM |
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On 1 Mai, 18:35, galathaea <galath...@gmail.com> wrote:
what medium?
I want to simulate scattering effects in the atmosphere, so air is the
medium.
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| User: "galathaea" |
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| Title: Re: Rayleigh scattering coefficients |
01 May 2007 01:41:41 PM |
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On May 1, 10:03 am, Jim <timm.von.puttka...@googlemail.com> wrote:
On 1 Mai, 18:35, galathaea <galath...@gmail.com> wrote:
what medium?
I want to simulate scattering effects in the atmosphere, so air is the
medium.
there are a number of journal articles on such simulations
that include the the data you are looking for
for example
http://adsabs.harvard.edu/abs/1989ApOpt..28..425P
http://adsabs.harvard.edu/abs/1984P&SS...32..785B
do you have online access to journals
( through a university - for instance )
?
if not i think the data available is more limited
at least that i am aware
i did some similar simulations years ago
as a part of a project on greenhouse affects
and i know the literature is full of this data if you do the footwork
check environmental magazines and astronomy/planetary research
as well as the obvious optics magazines
the info is spread pretty wide
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
galathaea: prankster, fablist, magician, liar
.
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| User: "Jim" |
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| Title: Re: Rayleigh scattering coefficients |
01 May 2007 02:03:37 PM |
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On May 1, 10:03 am, Jim <timm.von.puttka...@googlemail.com> wrote:
On 1 Mai, 18:35, galathaea <galath...@gmail.com> wrote:
what medium?
I want to simulate scattering effects in the atmosphere, so air is the
medium.
there are a number of journal articles on such simulations
that include the the data you are looking for
for example
http://adsabs.harvard.edu/abs/1989ApOpt..28..425P
http://adsabs.harvard.edu/abs/1984P&SS...32..785B
do you have online access to journals
( through a university - for instance )
?
if not i think the data available is more limited
at least that i am aware
i did some similar simulations years ago
as a part of a project on greenhouse affects
and i know the literature is full of this data if you do the footwork
check environmental magazines and astronomy/planetary research
as well as the obvious optics magazines
the info is spread pretty wide
Unfortunately, I still go to school and have no access to these
journals. Paying 30$ for each article without knowing whether it
contains the information I really look for is not that good either. Do
you know of some openly accessible resources that contain the data I'm
looking for?
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| User: "Timo A. Nieminen" |
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| Title: Re: Rayleigh scattering coefficients |
01 May 2007 02:36:31 PM |
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On Wed, 1 May 2007, Jim wrote:
On May 1, 10:03 am, Jim <timm.von.puttka...@googlemail.com> wrote:
On 1 Mai, 18:35, galathaea <galath...@gmail.com> wrote:
what medium?
I want to simulate scattering effects in the atmosphere, so air is the
medium.
there are a number of journal articles on such simulations
that include the the data you are looking for
for example
http://adsabs.harvard.edu/abs/1989ApOpt..28..425P
http://adsabs.harvard.edu/abs/1984P&SS...32..785B
do you have online access to journals
( through a university - for instance )
?
if not i think the data available is more limited
at least that i am aware
i did some similar simulations years ago
as a part of a project on greenhouse affects
and i know the literature is full of this data if you do the footwork
check environmental magazines and astronomy/planetary research
as well as the obvious optics magazines
the info is spread pretty wide
Unfortunately, I still go to school and have no access to these
journals. Paying 30$ for each article without knowing whether it
contains the information I really look for is not that good either. Do
you know of some openly accessible resources that contain the data I'm
looking for?
What you need you know are the sizes and refractive indices of the
scatterers. The basic formulae are available online, courtesy of
wikipedia. Standard procedure is to assume that the scatterers are
spherical, which works OK for small (ie Rayleigh) scatterers.
"Scattering effects in the atmosphere" is not very specific. Dust?
Raindrops? What, in particular are you interested in?
Philip Laven has a nice computer program that he has made freely available
to do scattering calculations. This is for larger spherical particles,
such as raindrops, and can simulate rainbows and the like. Look for it at
http://www.philiplaven.com/
if you're interested.
Scattering gets fairly heavy-duty as far as the maths is concerned quite
quickly. Many of the papers will be largely impenetrable; don't bother
with them, get a good book instead. If this is a long-term interest, buy
van de Hulst's book, Light scattering by small particles, a cheap Dover
reprint, US$14.95 the last time I bought a copy.
Craig Bohren has written some pop science books on scattering; I haven't
read these, but have read other stuff by him; he writes very well, and
these should be very worthwhile reading.
Perhaps you're not interested in scattering as such, but in radiative
transfer? Google for the magic words "radiative transfer" and you will
find stuff. Wikipedia has the basics, and links to free software for
atmospheric RT.
--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
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| User: "Jim" |
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| Title: Re: Rayleigh scattering coefficients |
02 May 2007 12:41:15 AM |
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On 1 Mai, 21:36, "Timo A. Nieminen" <t...@physics.uq.edu.au> wrote:
What you need you know are the sizes and refractive indices of the
scatterers. The basic formulae are available online, courtesy of
wikipedia. Standard procedure is to assume that the scatterers are
spherical, which works OK for small (ie Rayleigh) scatterers.
"Scattering effects in the atmosphere" is not very specific. Dust?
Raindrops? What, in particular are you interested in?
Philip Laven has a nice computer program that he has made freely available
to do scattering calculations. This is for larger spherical particles,
such as raindrops, and can simulate rainbows and the like. Look for it at
http://www.philiplaven.com/
if you're interested.
Scattering gets fairly heavy-duty as far as the maths is concerned quite
quickly. Many of the papers will be largely impenetrable; don't bother
with them, get a good book instead. If this is a long-term interest, buy
van de Hulst's book, Light scattering by small particles, a cheap Dover
reprint, US$14.95 the last time I bought a copy.
Craig Bohren has written some pop science books on scattering; I haven't
read these, but have read other stuff by him; he writes very well, and
these should be very worthwhile reading.
Perhaps you're not interested in scattering as such, but in radiative
transfer? Google for the magic words "radiative transfer" and you will
find stuff. Wikipedia has the basics, and links to free software for
atmospheric RT.
--
Timo Nieminen - Home page:http://www.physics.uq.edu.au/people/nieminen/
E-prints:http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits:http://www.users.bigpond.com/timo_nieminen/spirits.html
I want to render the sky on the basis of physical laws (so indeed
radiative transfer is my main interest).
I'm interested in how light is scattered by molecules in the air
(which is described by Rayleigh scattering).
"Light scattering by small particles" looks pretty interesting, I
think that I will buy a copy. Does it contain scattering coefficients?
My problem is that I am not sure whether parts of my calculations are
right, so it would help if I could compare my results to some
empirical data.
.
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| User: "galathaea" |
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| Title: Re: Rayleigh scattering coefficients |
02 May 2007 01:44:03 AM |
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On May 1, 10:41 pm, Jim <timm.von.puttka...@googlemail.com> wrote:
I want to render the sky on the basis of physical laws (so indeed
radiative transfer is my main interest).
I'm interested in how light is scattered by molecules in the air
(which is described by Rayleigh scattering).
"Light scattering by small particles" looks pretty interesting, I
think that I will buy a copy. Does it contain scattering coefficients?
My problem is that I am not sure whether parts of my calculations are
right, so it would help if I could compare my results to some
empirical data.
there are a number of computer graphics heuristics
for realistic atmosphere rendering
that take into account rayleigh scattering, etc.
see
http://www.mpi-inf.mpg.de/~lintu/papers/wscg05.pdf
there they use OPAC for calculating extinction and scattering
coefficients
also
http://www.math.zju.edu.cn/webpagenew/UploadFiles/AttachFiles/2004123019433575.pdf
and others
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
galathaea: prankster, fablist, magician, liar
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| User: "Jim" |
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| Title: Re: Rayleigh scattering coefficients |
02 May 2007 04:49:40 AM |
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On 2 Mai, 08:44, galathaea <galath...@gmail.com> wrote:
On May 1, 10:41 pm, Jim <timm.von.puttka...@googlemail.com> wrote:
I want to render the sky on the basis of physical laws (so indeed
radiative transfer is my main interest).
I'm interested in how light is scattered by molecules in the air
(which is described by Rayleigh scattering).
"Light scattering by small particles" looks pretty interesting, I
think that I will buy a copy. Does it contain scattering coefficients?
My problem is that I am not sure whether parts of my calculations are
right, so it would help if I could compare my results to some
empirical data.
there are a number of computer graphics heuristics
for realistic atmosphere rendering
that take into account rayleigh scattering, etc.
see
http://www.mpi-inf.mpg.de/~lintu/papers/wscg05.pdf
there they use OPAC for calculating extinction and scattering
coefficients
alsohttp://www.math.zju.edu.cn/webpagenew/UploadFiles/AttachFiles/2004123...
and others
I already know the article "Realistic Solar Disc Rendering" and I
have, like them, used OPAC for calculating absorption and scattering
coefficients for aerosol particles (here Mie scattering applies). For
Rayleigh scattering however they make use of tabulated data:
"Values for the wavelength-dependent scattering
coefficient sigma_air of air molecules are taken from
Nagel et al."
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| User: "Timo Nieminen" |
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| Title: Re: Rayleigh scattering coefficients |
02 May 2007 11:41:50 PM |
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On Wed, 1 May 2007, Jim wrote:
I want to render the sky on the basis of physical laws (so indeed
radiative transfer is my main interest).
I'm interested in how light is scattered by molecules in the air
(which is described by Rayleigh scattering).
There's a nice book chapter by Craig Bohren, on atmospheric optics,
covering the basics, which you can find via googling for
[bohren "atmospheric optics"]. A more general search for "atmospheric
optics" will bring other stuff that should interest you.
"Light scattering by small particles" looks pretty interesting, I
think that I will buy a copy. Does it contain scattering coefficients?
My problem is that I am not sure whether parts of my calculations are
right, so it would help if I could compare my results to some
empirical data.
It doesn't cover scattering by molecules in detail, but does cover
propagation of light in a medium with scatterers, and scattering by
particles much smaller than the wavelength, which is the basic maths for
what you want. Section 4.5 does cover molecular scattering. Chapter 20 is
all about atmospheric optics.
--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
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