Re: [Phys-L] Absorption and Scattering of IR By CO2 Gas

["Zani, Gerald" <gerald_zani@brown.edu>]

If you have a thermal camera that offers manual control of the temperature
scale then perform the following procedure to demonstrate the IR scattering
of light by CO2 gas.

Set up your CO2 chamber *two meters* away from a blank wall.

Turn on the camera. Focus the lens on the CO2 chamber. Do not focus on the
wall. Make sure that the camera looks through the chamber to the blank
wall. Nothing else.

Go into the camera menu. Override the automatic temperature scale. Set the
temperature scale to manual. Manually adjust the temperature scale so that *the
wall is at the lowest end of the displayed temperature scale and the upper
end of the scale is* *no more than 3 degrees Celsius above the low end*.

Have an IR source, such as a person stand in front of the blank wall, two
meters distant from the CO2 chamber. Focus on the IR source/person.
Introduce the CO2 gas to the chamber.
Wait for the introduced CO2 gas to warm up to room temperature and observe
the IR scattering.

See attached TPT article;
APRIL 01 2019
A Demonstration of the Infrared Activity of Carbon Dioxide Special
Collection: Teaching about the environment, sustainability, and climate
change (2010-2022)
Philip G. Sieg; William Berner; Peter K. Harnish; Philip C. Nelson
TPT 57, 246–249 (2019)

See attached Physics Today article;
Infrared radiation and planetary temperature
By Raymond T. Pierrehumbert
January 2011 Physics Today

Note: I have not tried this myself. This procedure is described in the
attached article.
Hope this helps.
- Jerry

On Tue, Jul 30, 2024 at 3:04 PM Zeke Kossover <zeke.kossover@gmail.com>
wrote:

> I've been working on a similar project at the Exploratorium. After seeing this
> video from the Perimeter Institute <https://youtu.be/l7rqlvzWrEw?t=82>, I
> have been trying to duplicate their results. It's not been going well. I
> even talked to the production manager and videographer to find out what
> they did, and I'm still not getting anything different between carbon
> dioxide and plain air. Heck, I can't reliably get a difference between
> regular air and sulfur hexafluoride, a very powerful and expensive
> greenhouse gas. It's driving me crazy.
>
> Zeke Kossover
>
> Exploratorium
>
> On Tue, Jul 30, 2024, 8:14 AM Paul Nord <Paul.Nord@valpo.edu> wrote:
>
> > JZ,
> >
> > There are a variety of cameras.  I've got the little FLIRone.  It does
> > have the ability to lock the temperature scale.  The default is an
> > automatic range as you suggest.  It gives a weird impression about the
> > nature of the world until you figure it out.  I know that when inspecting
> > my walls at home in the winter it can see some cold spots where the
> > insulation has gaps or has settled.  But if I check the temperature
> > differences of those spots, they're just a few degrees colder which
> > suggests that the problem is relatively minor.
> >
> > I'm sure that the setting you need is possible.
> >
> > Paul
> >
> >
> > On Tue, Jul 30, 2024 at 9:55 AM Zani, Gerald <gerald_zani@brown.edu>
> > wrote:
> >
> > > Dear Tap-l,
> > >
> > > We have a FLIR IR thermal camera and want to use it to show that CO2 gas
> > > absorbs IR.
> > >
> > > Does anyone do this?
> > > How?
> > >
> > > For our demo, we made a tank and filled it with CO2 gas, as shown in
> > > this video:
> > > https://www.youtube.com/watch?v=Ot5n9m4whaw&ab_channel=m1der1
> > >
> > > But we are having a problem.
> > >
> > > It might be due to the default setting for the thermal camera, which is
> > > for automatic thermal tuning?
> > > If So, then when the image gets dimmer due to the IR light scattering by
> > > the CO2 gas, the camera is automatically tuning the thermal span and the
> > > thermal level. This defeats the demo. It appears that the CO2 is not
> > > scattering the light.
> > >
> > > To prevent this problem, we must go into the camera menu to adjust the
> > > brightness of a FLIR thermal camera so it has a manual setting, not
> > > automatic and we need to find the thermal cameras Temperature Scale
> > > settings, which have a span and a level.
> > >
> > > We need to change the temperature scale, the temperature span and the
> > > temperature level. This process is called thermal tuning.
> > >
> > > Does anyone know how to do this?
> > >
> > > Thanks,
> > > - JZ
> > >
> > > --
> > > Gerald Zani
> > > Senior Engineering Technician
> > > Brown University School of Engineering
> > > (401) 863-9571
> > >
> > > To unsubscribe from this group and stop receiving emails from it, send
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-- 
Gerald Zani
Senior Engineering Technician
Brown University School of Engineering
(401) 863-9571