Reply To: Questions regarding DPF.

[KeithPickering]

Brian H wrote: About 3% of incident radiation reaches the surface of Venus, as far as most sources can tell. Significant ground re-radiation in longer wavelengths absorbed by CO2 and then re-re-radiated (?!) thus doesn’t occur, which is the basis of any “greenhouse” effect.

So if there’s no greenhouse effect, why is Venus hotter than Mercury? I’ve got a theory that explains the phenomena. You’ve got bupkus.

Meanwhile, it doesn’t matter whether the incoming solar radiation is absorbed by the surface or the clouds. Greenhouse works either way, because there’s still a lot of CO2 above the cloud layer. (Cloud tops of Venus are at about 50 km, pressure 0.1 bar, with a 96% CO2 atmosphere, that puts roughly 300 times more CO2 above Venus’s cloudtops than above anywhere on the surface of the Earth.)

And that 3%? What happens to it? It gets radiated away in IR, then gets absorbed, re-radiated, absorbed, re-radiated, until it eventually hits a CO2 molecule that absorbs the energy and keeps it as heat. So much, much less than 3% of that 3% ever gets out again. Which is why the surface is so hot.

It certainly cannot be taken as any kind of “example”, cautionary, horrible, or otherwise.

In other words: you’ve got bupkus.