Re: Whoops! The Atlantic Makes Trump Look EPIC In Cover Intended as a Smear

Lynn McGuire wrote:

On 9/18/2024 7:35 PM, William Hyde wrote:
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Chemical saturation limits EVERYTHING but is rarely taken into account.

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I take it you mean saturation in the IR spectrum.  If you have some other intent with "chemical" saturation, please enlighten us.
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Radiative  transfer calculations, to which you seem to be referring, take into account the known laws of physics.  "Saturation" is not some add-on to these laws but a consequence of them.
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Alas for us, "saturation" does not limit greenhouse warming for several reasons, not least of which is that the atmosphere is not saturated, and will not soon be saturated, over most of the emission spectrum.
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William Hyde

 If the atmosphere never reached saturation then it would never rain or snow.

Phase transitions are complicated - though that is something you know well from your own work.
As a matter of fact, snow can form before saturation, owing to the presence of cloud condensation nuclei.
But on the other hand, without such CCN the water vapour content of the atmosphere can go over 100% saturation, albeit only slightly, and water droplets can remain liquid at temperatures as low as -36C. Unfortunately for aviators.
The wikipedia page on this seems decent:
https://en.wikipedia.org/wiki/Cloud_physics#Adding_moisture_to_the_air
I assumed that you had erred in your comment above and were referring to saturation in IR bands, a topic you have raised before.  That seems clear from the nature of my reply.
I was wrong to make that assumption.  Sorry about that.
   Those are just the obvious atmospheric saturation limits.
In what sense is that a problem for the models?
   There

are many more that cause discontinuities in all models.

But it is not clear what your comment about "chemical saturation" means.
When a model predicts saturation of water vapour, it produces condensation - this is how models predict precipitation, though naturally not all condensation precipitates.  It certainly wasn't the easiest component of the models to create, but we've had working versions for decades. As with everything in the geosciences, there's certainly room for improvement even now.
Tell me more about these "discontinuities".  Why do you claim that they are "rarely  taken into account"?
It's a long time ago now, but I worked on a GCM and still have some contacts in the community.  Tell me what we "haven't taken into account" so I can pass it on.
William Hyde