Re: OT: Post Turtle

On Tue, 24 Jun 2008 09:27:44 -0700, John Larkin
<jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:


That's a separate issue. It's like cascading filters, electrical or
optical, a linear effect as far as I know. The issue here is whether
adding CO2 to the atmosphere has much effect, through pressure
broadening, on absorption by other gasses. Nobody here seems to know.

I was accused of being ignorant because I didn't know, so I suppose
that makes us all ignorant. That hasn't stopped people from lecturing
me.

John





Ok, a couple of thoughts on this...

The only way I can see 'pressure' broadening having an effect, would
be that the Partial Pressure of CO2 has increased due to the
additional amounts in the atmosphere. Now, if this is so, then I
expect that two measurements would quickly show and measure the
effects.

One, a laboratory setup, with a, let us say, 100 meter tube of gas.
Using an interferometry setup, you could measure the
absorption/scattering of a STP mix of air with two controlled levels
of CO2, one with the level of say 200 years ago, and one with the
presently measured CO2 level. Heck, you could even DOUBLE the present
CO2 level for a third measurement. You could then, without a doubt,
measure the pressure broadening effects of CO2. If you needed to
somehow measure the effects at different altitudes, just reducing the
pressure and/or temperature could give you a whole set of
measurements. Sounds like a simple atmospheric physics experiment
which should pretty much put the issue to rest.

Second, there should be full spectrum measurements, probably with an
interferomentric spectroscope, of our normal solar insolation at some
point or points both above and below the atmosphere. That should tell
us what effects the CO2 is having on the levels of insolation, and if
any 'pressure broadening' is actually effecting the IR levels we
receive...

But then, I am an experimentalist, not a theorist! ;-)

Charlie
.

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