-- R.G. Menzies
LIBERTARIAN/CONSERVATIVE DIGEST AND COMMENTARY FROM AN ACADEMIC PSYCHOLOGIST in Brisbane, Australia. My academic publications are widely read
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"Adiabatic" effects and the temperature of Venus
Adiabatic effects -- in this case the effect of pressure on the temperature of gases -- have been known for centuries, but they have only recently been remembered in explaining earth's temperature. But they explain the temperature of Venus best of all -- unlike the quite fraudulent "runaway greenhouse effect" that is usually invoked to explain why Venus is superheated.
Note that even on Earth in places like like the Dead Sea, or Death Valley, or the deep gold mines in South Africa, which are all below sea level, temperatures are significantly higher than in comparable regions at sea level, and that has nothing to do with the CO2 content of the atmosphere but rather due to adiabatic compression.
The first problem is that the surface of Venus receives no direct sunshine. The Venusian atmosphere is full of dense, high clouds “30–40 km thick with bases at 30–35 km altitude.“ The way a greenhouse effect works is by shortwave radiation warming the ground, and greenhouse gases impeding the return of long wave radiation to space. Since there is very little sunshine reaching below 30km on Venus, it does not warm the surface much. This is further evidenced by the fact that there is almost no difference in temperature on Venus between day and night. It is just as hot during their very long (1400 hours) nights, so the 485C temperatures can not be due to solar heating and a resultant greenhouse effect. The days on Venus are dim and the nights are pitch black.
The next problem is that the albedo of Venus is very high, due to the 100% cloud cover. At least 65% of the sunshine received by Venus is immediately reflected back into space. Even the upper atmosphere doesn’t receive a lot of sunshine. The top of Venus’ atmosphere receives 1.9 times as much solar radiation as earth, but the albedo is more than double earth’s – so the net effect is that Venus’ upper atmosphere receives a lower TSI than earth.
The third problem is that Venus has almost no water vapor in the atmosphere. The concentration of water vapor is about one thousand times greater on earth.
Water vapor is a much more important greenhouse gas than CO2, because it absorbs a wider spectrum of infrared light
The effects of increasing CO2 decay logarithmically. Each doubling of CO2 increases temperatures by 2-3C. So if earth went from .04% CO2 to 100% CO2, it would raise temperatures by less than 25-36C.
Even worse, if earth’s atmosphere had almost no water (like Venus) temperatures would be much colder – like the Arctic. The excess CO2 does not begin to compensate for the lack of H2O. Water vapour accounts for 70-95% of the greenhouse effect on earth. The whole basis of the CAGW argument is that H2O feedback will overwhelm the system, yet Venus has essentially no H2O to feed back. CAGW proponents are talking out of both sides of their mouth.
So why is Venus hot? Because it has an extremely high atmospheric pressure. The atmospheric pressure on Venus is 92X greater than earth. Temperatures in Earth’s atmosphere warm over 80C going from 20 kPa (altitude 15km) to 100 kPa (sea level.) That is why mountains are much colder than the deserts which lie at their base.
The atmospheric pressure on Venus is greater than 9,000 kPa. At those pressures, we would expect Venus to be very hot. Much, much hotter than Death Valley.
This is very close to what we see on Venus. The high temperatures there can be almost completely explained by atmospheric pressure – not composition. If 90% of the CO2 in Venus atmosphere was replaced by Nitrogen, it would change temperatures there by only a few tens of degrees.
More HERE (See the original for links, graphics etc.)
Update here
German physicists Gerlich and Tscheuschner are also very scathing on the matter. Excerpt:
In the speculative discussion around the existence of an atmospheric natural greenhouse effect or the existence of an atmospheric CO2 greenhouse effect it is sometimes stated that the greenhouse effect could modify the temperature profile of the Earth’s atmosphere.
This conjecture is related to another popular but incorrect idea communicated by some proponents of the global warming hypothesis, namely the hypothesis that the temperatures of the Venus are due to a greenhouse effect. For instance, in their book “Der Klimawandel. Diagnose, Prognose, Therapie” (Climate Change. Diagnosis, Prognosis, Therapy) “two leading international experts”, Hans-Joachim Schellnhuber and Stefan Rahmstorf, present a “compact and understandable review” of “climate change” to the general public.
On page 32 they explicitly refer to the “power” of the “greenhouse effect” on the Venus. The claim of Rahmstorf and Schellhuber is that the high venusian surface temperatures somewhere between 400 and 500 Celsius degrees are due to an atmospheric CO2 greenhouse effect.
Of course, they are not. On the one hand, since the venusian atmosphere is opaque to visible light, the central assumption of the greenhouse hypotheses is not obeyed. On the other hand, if one compares the temperature and pressure profiles of Venus and Earth, one immediately will see that they are both very similar.
An important difference is the atmospheric pressure on the ground, which is approximately two orders higher than on the Earth. At 50 km altitude the venusian atmospheric pressure corresponds to the normal pressure on the Earth with temperatures at approximately 37 Celsius degrees. [i.e. a temperature fairly common in tropical regions on earth --JR]
Posted by John J. Ray (M.A.; Ph.D.). For a daily critique of Leftist activities, see DISSECTING LEFTISM. To keep up with attacks on free speech see TONGUE-TIED. Also, don't forget your daily roundup of pro-environment but anti-Greenie news and commentary at GREENIE WATCH . Email me here
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