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Alternate explanations for Venus

Travis

Misanthrope of the Mountains
Travis
Joined
Mar 31, 2007
Messages
24,133
I've encountered someone who doesn't buy the conventional explanation for why Venus has such hellish conditions. It apparently upsets him for some reason.

So has anyone ever heard of any alternate explanations? Would someone like to speculate wildly and irresponsibly? Might there really be mermaids, sexually aroused women and jungles down there that the landers missed? :p
 
Travis said:
I've encountered someone who doesn't buy the conventional explanation for why Venus has such hellish conditions. It apparently upsets him for some reason.

So has anyone ever heard of any alternate explanations? Would someone like to speculate wildly and irresponsibly? Might there really be mermaids, sexually aroused women and jungles down there that the landers missed? :p
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maybe that is why i say "good morning' each am to venus.
 
Travis said:
I've encountered someone who doesn't buy the conventional explanation for why Venus has such hellish conditions. It apparently upsets him for some reason.
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Well, it used to be fantasized to have strange and exotic life under them clouds. I suppose we were all a little disappointed at the news that it makes Hell look like a cool place.

So has anyone ever heard of any alternate explanations? Would someone like to speculate wildly and irresponsibly? Might there really be mermaids, sexually aroused women and jungles down there that the landers missed? :p
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I think the conditions at the poles are not much hotter than the hottest locations on Earth where we find life. So life on Venus is not entirely ruled out, just very unlikely.

Hans
 
Bikewer said:
Well, there's always Velikovsky.....
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I generally try to forget about him.

Dancing David said:
Here you go, we had a thread about this too,
http://junkscience.com/Greenhouse/venus.html

ETA:


ah, the memories:
http://www.internationalskeptics.co...hp?t=178527&highlight=venus+greenhouse+effect
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Ah. Seems you know what is behind this.
RenaissanceBiker said:
Where do you meet these people and why do you keep going back?
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I happen to be related to this person.
 
MRC_Hans said:
I think the conditions at the poles are not much hotter than the hottest locations on Earth where we find life. So life on Venus is not entirely ruled out, just very unlikely.
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Although you have to remember it's not just the temperature that's the problem. The high pressure, carbon dioxide atmosphere and sulphuric acid rain may also cause slight problems. If life is there, it certainly won't be anything like Earth life.
 
MRC_Hans said:
I think the conditions at the poles are not much hotter than the hottest locations on Earth where we find life. So life on Venus is not entirely ruled out, just very unlikely.
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On Venus there isn't all that much difference in surface temperature between the poles and equator
 
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Cuddles said:
Although you have to remember it's not just the temperature that's the problem. The high pressure, carbon dioxide atmosphere and sulphuric acid rain may also cause slight problems. If life is there, it certainly won't be anything like Earth life.
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To the last: Certainly not. Will it be anywhere?

To the first: Sure, but such is also a very energy-rich environment. Life there needs no sophisticated processes to get energy. Rather it needs some processes to protect itself against all that energy.

But we see life that prospers in diesel fuel, we see life in oxygen free 100+degC environments, right here on Earth.

Certainly, we should not expect anything but the most simple life forms on Venus, if at all.

Hans
 
Cuddles said:
Although you have to remember it's not just the temperature that's the problem. The high pressure, carbon dioxide atmosphere and sulphuric acid rain may also cause slight problems. If life is there, it certainly won't be anything like Earth life.
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Anyone else heard about the speculation of a "habitable zone" in the upper atmosphere of Venus? I can't find anything right off, but I do recall reading about it, and while it sounded plausible enough, was probably more wishfull thinking than serious hypothesis.
 
The problem with the 'greenhouse effect' explanation is that the average surface temperature of Venus is far higher (both day and night sides) than the black body radiation would explain (which places a limit on the average temperature of a body). You would need to explain why the average surface temperature (and associated atmospheric temperature) is so much higher than a perfectly absorbtive solid physical body. The high pressure of the atmosphere would enable it to radiate more of the surface heat into space because of its improved conductivity.

Since virtually no light/radiation even reaches the surface these days you can't even have a functioning greenhouse (where the surface is heated by radiation, then re-radiates the energy). It's basically dark on the surface so no radiant energy is reaching it.

A good guess is that there is significant geothermal heat being held in place, far more than we encounter on the earth.

BTW I frequently come across people attempting to use Boyles laws to claim that increasing temperature will increase atmospheric pressure. It WILL NOT. The classic gas laws apply to a closed chamber. Atmospheric gas pressure is caused entirely by the weight of a column of gas. If the gas is heated, it expands farther into space (unless it redistributes in the case of local heating) but it will NOT increase pressure just because the temperature increased.
 
jayh said:
Since virtually no light/radiation even reaches the surface these days you can't even have a functioning greenhouse (where the surface is heated by radiation, then re-radiates the energy). It's basically dark on the surface so no radiant energy is reaching it.

A good guess is that there is significant geothermal heat being held in place, far more than we encounter on the earth.
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This isn't really true. There IS light on the surface, which is why the surface probes were able to take photos. The light level is much lower at the surface, so it doesn't provide a LOT of heating, but it provides some.

And some heating is really all you need. Well, that plus a really thick atmosphere. A little bit of heating (and it doesn't take much) sets up convection. Convection creates a vertical temperature gradient through the adiabatic lapse rate. With a really thick atmosphere, you get a huge temperature difference. That gradient will basically apply until you get high enough in the atmosphere to start radiating significant amounts of thermal energy into space, which doesn't happen until pretty high up for Venus.

So the high surface temperatures are not simply the result of greenhouse effects, but you don't need geothermal heating to explain it either. The same atmospheric composition but with less atmosphere would produce a cooler surface temperature. But the atmospheric composition isn't irrelevant either, because that determines where your crossover is between convective heat loss (where adiabatic lapse rate controls the gradient) and radiative heat loss. And the higher up that transition occurs, the hotter the surface is.
 
Ziggurat said:
This isn't really true. There IS light on the surface, which is why the surface probes were able to take photos. The light level is much lower at the surface, so it doesn't provide a LOT of heating, but it provides some.

And some heating is really all you need. Well, that plus a really thick atmosphere. A little bit of heating (and it doesn't take much) sets up convection. Convection creates a vertical temperature gradient through the adiabatic lapse rate. With a really thick atmosphere, you get a huge temperature difference. That gradient will basically apply until you get high enough in the atmosphere to start radiating significant amounts of thermal energy into space, which doesn't happen until pretty high up for Venus.

So the high surface temperatures are not simply the result of greenhouse effects, but you don't need geothermal heating to explain it either. The same atmospheric composition but with less atmosphere would produce a cooler surface temperature. But the atmospheric composition isn't irrelevant either, because that determines where your crossover is between convective heat loss (where adiabatic lapse rate controls the gradient) and radiative heat loss. And the higher up that transition occurs, the hotter the surface is.
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If the Atmosphere of Venus was the same mass but different composition it would not be as hot as it is. If is were the same mass but composed entirely of of gasses that were transparent to both IR and visible light its surface temperature would be approximately the same as it's black-body temperature.

Atmospheric height is not a constant so you can't just take the laps rate and height of the atmosphere and use it to a planets calculate surface temperature. To the nearest approximation, what you really have is surface temperature being determined by the amount (mass) of greenhouse gasses and isolation, and lapse rate determining the height of the atmosphere. Pressure on it's own has no impact on planetary temperature.
 
jayh said:
The problem with the 'greenhouse effect' explanation is that the average surface temperature of Venus is far higher (both day and night sides) than the black body radiation would explain (which places a limit on the average temperature of a body).
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Greenhouse gasses have precisely that effect, they cause a planet to have surface temperatures above it's black body temperature.
 
lomiller said:
Greenhouse gasses have precisely that effect, they cause a planet to have surface temperatures above it's black body temperature.
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They can create a localized temperature (such as in parts of the surface) somewhat above the black body temperature, but not the entire planet. As the atmosphere heats, it too becomes a radiator (and effectively part of the surface) and a dense atmosphere can effectively cool by convection. It's not a limitless process, it can only locally tilt the equilibrium so much before other factors work to equalize things.

You don't get a magic one-way valve for heat. Greenhouse effects occur when you get a rather extreme difference in heat absorption between the surface and the atmosphere, and the surface re-radiating additional energy as infrared. when the radiant energy striking the surface is not not strong (as in Venus) you will not get that differential.

With the heavy cloud cover you get a great deal of the sun's energy reflected, and a substantial amount going to heating the upper atmosphere where it will effectively be re-radiated.
 
lomiller said:
If the Atmosphere of Venus was the same mass but different composition it would not be as hot as it is. If is were the same mass but composed entirely of of gasses that were transparent to both IR and visible light its surface temperature would be approximately the same as it's black-body temperature.
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Basically every gas becomes opaque at some depth to at least some segment of the visible/IR spectrum. Which means the temperature profile of basically any atmosphere will become dominated by the adiabatic lapse rate below its optical depth, because it won't be able to radiate heat away below that depth (it will only radiate in the same window it absorbs). What gas you use determines what the relevant windows are, and what the optical depth is, but the idea is the same regardless of what gas you use.

Atmospheric height is not a constant so you can't just take the laps rate and height of the atmosphere and use it to a planets calculate surface temperature.
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I'm not suggesting that. In fact, you should do the reverse. You start on the outside and work inwards. Find out how much gas you need to become opaque to the relevant window, figure out the temperature and pressure at that depth based on blackbody characteristics and the amount of gas required, then apply the lapse rate below that until you've accounted for the entire atmospheric mass. And the more atmospheric mass you have, the deeper you need to go, and the higher the ground temperature that adiabatic lapse rate produces. Note also that I'm specifically stating that the adiabatic lapse rate does NOT apply to the entire atmosphere. But the more atmosphere you have, the more of it that lapse rate applies to.

To the nearest approximation, what you really have is surface temperature being determined by the amount (mass) of greenhouse gasses and isolation, and lapse rate determining the height of the atmosphere. Pressure on it's own has no impact on planetary temperature.
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Mass and pressure are directly proportional here. The pressure isn't what produces the temperature difference, but I didn't claim it was.
 
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