On Sun, 21 Oct 2018 15:26:01 -0600
Chris L Peterson wrote:

Actually, it was proposed by Andrew Ingersoll,

Possibly. I was intrigued by Sagan's paper on interstellar flight
and went to the UCLA library to look up everything Sagan had
written. This might have been on the same page or in the same
journal as something Sagan wrote, but I don't think so. Do you have
a reference?

Neither Sagan or Ingersoll seems to have their early serious
publications listed in wikipedia. That is as far as I can pursue it
now.

and it remains the most
widely accepted hypothesis for the evolution of the venusian
atmosphere.

Widely accepted among creationists perhaps. The idea that planets
originally held an earth-like atmosphere is absurd. Even the earth
didn't have that. In his video Ingersoll says Earth and Venus
originally had similar atmospheres and they evolved in different
directions. That is the same thing I am saying. Indeed all the
planets began with similar atmospheres and evolved in different
directions. It is noteworthy that Mars has a similar atmosphere to
Venus (just less of it). No runaway greenhouse effect there.

https://www.youtube.com/watch?v=zqmHWbPHDlI

It is supported both by modeling,

Ah, modeling. I can write computer models too. It shows that such a
thing is possible. Nothing more.

and by the very high D/H
ratio on Venus.

A high D/H ratio is exactly what you would expect if most of the
hydrogen were simply boiled away, as I suggested. It says nothing
about whether there was an ocean or not. The paper that
I read suggested that at one time an earth-like environment
prevailed on Venus, and the greenhouse effect made the water boil
away. It is not necessary to have had an earth-like environment in
the first place for the hydrogen to be driven off due to less
gravity and closer distance to the sun. The lighter isotopes will
always be driven away more quickly.

In the case of Venus, water would have been the driving greenhouse
gas, not CO2.

Point taken. My remark was about Venus being so
hot today: hotter than Mercury, hot enough to melt lead. What needs
to be pointed out is that at elevations with equivalent atmospheric
densities, Venus isn't hot. On earth every time we descend to a
lower elevation with higher pressure, the temperature increases: about
2C per thousand meters. On Venus it should be the same, but the
pressure at the surface is 92 times the pressure on the surface of the
earth. It is the atmospheric pressure and not the greenhouse effect
that keeps the surface of Venus so hot today.


--
I'm Trawley Trash, and you haven't heard the last of me yet.