Greenhouse Effect om Mars - Page 2

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Gingle Blingle Stoogleplex Frok Lorif Joiem Korknle


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Reply: 21



PostPosted: June 16, 2005 2:18 PM 

I think the real issue here is that every single thermometer sent up to Mars thus far has been so inaccurate. I imagine that the average temperature on Mars could also be measured without actually being on Mars, such as from infrared radiation, and therefore all those instruments must have been wrong too.

What we really need to worry about it adjusting all these instruments so that they measure correctly. Why isn't NASA addressing this? They must have something to hide.

Extra Sense


Posts: 1471

Reply: 22



PostPosted: June 16, 2005 2:23 PM 

Rocks, get a clue.

What do you mean by runaway greenhouse effect? Razz

As Martin have pointed out, the speed of cooling can be reduced by that effect, by half - at most. The result is that lower temps will be higher than without g-effect.

Our environmentalist idiots get excited by the word "greenhouse", but in the Universe each and every effect is as good as gold in its weight.

e Shocked s

Martin Gradwell


Posts: 323

Reply: 23



PostPosted: June 16, 2005 2:53 PM 

"CO2 on Mars is much more [i]attenuated[/i] than the greenhouse and non-greenhouse gasses on earth"

Yes, but the non-greenhouse gases are irrelevant to the greenhouse process. If they weren't irrelevant than they'd all be called greenhouse gases and there'd be no such thing as a non-greenhouse gas.

The greenhouse effect on Mars is real, and measurable, and huge.

Mars is on average about 1.5 times as far away from the sun as the Earth is. By the inverse square law, the intensity of the sunlight reaching it is 1/(1.5)^2 of the Earth's sunlight. That is, about 44 percent.

Other things being equal albedo-wise and greenhouse-wise, the temperature on Mars would be about 44% of the temperature on Earth. But we're talking absolute temperature here, which is measured in degrees Kelvin.

The mean temperature on Earth is 15 C according to
http://library.thinkquest.org/C005921/Earth/earth.htm
and that's 288 degrees K (to convert from C to K just add 273).

44% of 288 is 127 degrees K. That's minus 146 degrees C. The actual average temperature on Mars is -63 degrees C according to
http://library.thinkquest.org/C005921/Mars/marsSurf.htm

That's a whole 83 degrees Celsius warmer than you'd expect if Mars had just the same amount of greenhouse effect as Earth has. Almost as much as the difference between ice and steam on Earth.

And yet you will find plenty of sites saying that there's no greenhouse effect on Mars, or that it is negligible. This is because there is a "cold dry Mars" agenda which *requires* this assertion to be made, regardless of what science might have to say about it.

The thinkquest site also tells us that the max temperature on Mars is 20 degrees C.Think about it. That's five degrees warmer than Earth's average temperature. And it's not just in some tiny obscure spot, the Martian equivalent of Death Valley. There are vast swathes of Mars where the daytime temperature in summer reaches 20 degrees C. If Martian organisms can survive being temporarily frozen during the night (as many Earth organisms can) then their main problem during the day is excessively *high* temperatures. (Excessively high for organisms designed to cope with the cold, that is).

They're Rocks


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Reply: 24



PostPosted: June 16, 2005 2:57 PM 

Oh, ES, you're so transparent, and so silly. I knew all along you were trying to make the case that a runaway greenhouse effect is just some figment of environmentalist imagination, for otherwise, it would have occurred on Mars.

But, as always, you are daft. The greenhouse gas molecules are more attenuated on Mars, adn that's why more heat and light radiates back into space than on earth and hence there is no runaway greenhouse effect. Reasonable people (i.e., not you) will notice that we actually have a case study of runaway greenhouse: Venus.

But I know, ES. This is the brain-dead mainstream science of NASA imbeciles. We need happy-dappy, extra-strength, woo-woo NEW science from you, Favonio, RW, et all.

On the other hand, Gingle Blingle might have hit on something; The Thermometer Conspiracy.

They're Rocks


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Reply: 25



PostPosted: June 16, 2005 3:00 PM 

Martin, yes, there is a greenhouse effect on Mars -- I've already said this. What we are addressing is that given this fact, the Martian surface, according to ES, should be very hot. And, of course, that's a non sequitor, as I believe I've already shown.

Daniel


Posts: 991

Reply: 26



PostPosted: June 16, 2005 3:10 PM 

Hi Martin,
That assumes that 100% of all surface heat is coming from the Sun. A measurable amount should be coming from the planets interior (the molten core radiating outward) and from radioactive decay from throughout the interior (and probably at some surface or near surface areas) of Mars.

Daniel


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Reply: 27



PostPosted: June 16, 2005 3:12 PM 

That isn't to say there isn't SOME greenhouse processes going on - but the atmosphere's efficiency in trapping heat is a lot lower than the Earth's atmosphere.

They're Rocks


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Reply: 28



PostPosted: June 16, 2005 3:15 PM 

Sure there's a greenhouse effect going on. But ES has clumsily tried to create a reductio of the runaway greenhouse effect argument, and he has failed miserably. Now back to worrying about Martian concrete, ES. Twisted Evil

Daniel


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Reply: 29



PostPosted: June 16, 2005 3:26 PM 

ES - you narrow minded fool! The inner solar system is a wasteland of runaway greenhouse gases! Why on Earth, water is found not only in Liquid - but in Gas form as well! Who has ever heard of such a thing? Venus is suspected to be even hotter, but our Plutonian space probes, composed of state of the art Water Ice, have never been able to penetrate the outer layers ofits atmosphere.

At least Mars is somewhat habitable in its polar regions. During the Winter. At night.

Extra Sense


Posts: 1471

Reply: 30



PostPosted: June 16, 2005 3:30 PM 

What I was trying to show, is that greehouse effect considerations are not as primitive as rocks and daniel think.

Kyotoistas, commies and the rest of pseudoenvironmentalist idiots focus on the fossil fuel emissions, meanwhile deforestation and forest mismanagement are the culprits.

e Cool s

Martin Gradwell


Posts: 323

Reply: 31



PostPosted: June 16, 2005 3:34 PM 

re: reply 25: TR, You have, addmittedly, said that Mars "certainly does have some greenhouse effect". But in the same post you said

"the reason we don't (have a runaway greenhouse scenario) is flat out because the atmosphere is way too thin -- the amount of carbon dioxide is irrelevant."

The amount of carbon dioxide is certainly not irrelevant.However, the thickness of the atmosphere is. You could have an atmosphere significantly thinner that that of Mars, and it would have an even stronger greenhouse effect, if it was composed of CFCs.

You have also cited two sites, the first of which (starryskies.com) says "Mars density is so low that the carbon dioxide creates only a minor greenhouse effect" while the second (ucar.edu) says "a Mars atmosphere would leave us shivering in a Martian-type deep freeze". Both of these sites are spouting nonsense, and citing them does not help your case. A greenhouse effect which is consideraby stronger than the Earth's is not "minor", unless the word has some new definition of which I was previously unaware. And a Mars atmosphere, transplanted to Earth, would make the Earth very much hotter than it currently is. It would not "leave us shivering" unless the thermostat in our pressurized suits was set too low.

And Mars is "very hot", at least when compared to the temperature it would have if it had no greenhouse effect, or only Earth-levels of greenhouse effect.

Daniel


Posts: 991

Reply: 32



PostPosted: June 16, 2005 3:45 PM 

ES who ever said that fossil fuels alone were responsible for affecting the rise in Earth's average temperature? On the other hand, explain how artificially added Greenhouse gases not have some effect? Even if all they do is raise temperatures another degree over the next few decades, which is a fairly puny amount, it'll still be an economic burden worldwide...

Martin - you still haven't addressed the fact that Mars's atmosphere does a demonstratably worse job at retaining heat compared to Earth, as shown by overnight heat loss.

Daniel


Posts: 991

Reply: 33



PostPosted: June 16, 2005 4:04 PM 

Martin - all the sources I could find quote the effect of "greenhouse warming" of Mars to be on the order of raising temps by 5-10 degrees C. Do you have a link or reference to something that says otherwide?

Extra Sense


Posts: 1471

Reply: 34



PostPosted: June 16, 2005 4:09 PM 

Daniel,

this is a good example, of how much your understanding of things is wanting, be it Earth or Mars.

If CO2 is added by emissions, the actual concentrations could still fell if more than that CO2 were consumed by photosynthesis.

If all human CO2 emissions were eliminated including human breathing, the CO2 levels would still be rising because of deforestation and forest mismanagement.

e Shocked s

They're Rocks


Posts: no

Reply: 35



PostPosted: June 16, 2005 4:12 PM 

Martin, perhaps I misunderstand your argument, but I honestly don't see how you are arriving at these conclusions. How can you say that the thickness of the atomsphere doesn't count? Let's reduce this to a simplified idealization, which could never happen in the real world.

Suppose you had a planet that consisted of ten C02 molecules in its atmosphere. That's it: that's the entire atmosphere. In other words, it's 100 percent carbon dioxide!

Would there be a greenhouse effect? A runaway greenhouse effect? And if such an atmosphere were transferred to earth, would earth become warmer or cooler?

They're Rocks


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Reply: 36



PostPosted: June 16, 2005 4:42 PM 

this is a good example, of how much your understanding of things is wanting, be it Earth or Mars.

This from a guy who thinks there's an abandoned theme park on Mars.

If CO2 is added by emissions, the actual concentrations could still fell if more than that CO2 were consumed by photosynthesis.

But that's not happening, is it? Oh, wait, I know: deforestation. So...

If all human CO2 emissions were eliminated including human breathing, the CO2 levels would still be rising because of deforestation and forest mismanagement.

It'd be pretty hard for humans to practice deforestation, or forest mismanagement of any kind, if they weren't breathing.

But anyway. How about that concrete?

Martin Gradwell


Posts: 323

Reply: 37



PostPosted: June 16, 2005 4:44 PM 

Daniel: Re: reply 26.
You say "That assumes that 100% of all surface heat is coming from the Sun. A measurable amount should be coming from the planets interior (the molten core radiating outward) and from radioactive decay"

Yes, but the mainstream opinion is that there is less heat flow from the interior in the case of Mars than in the case of Earth.

http://www.academicpress.com/refer/solar/Contents/chap12_9.htm

Says, of Mars,
"Current average surface heat flow is estimated to be 40 mW/m2, as compared with the Earth's 75 mW/m2".

So this doesn't explain why the surface temperatures on Mars should be so much higher than we would expect if there was little or no greenhouse effect there. On the other hand it might help to explain why there is still some frozen CO2 at the poles - though the emerging new consensus seems to be that there is very little frozen CO2 and the poles are mostly ice.

Re: reply 32.
Temperature swings on Earth are lower, in general, than on Mars because of the moderating effects of water. One effect is that freeze/thaw, where it occurs, keeps the temperature at or very close to 0 degrees C. A liquid water/Ice mix, being melted, will stay at 0 C until the melting is complete, and that requires the input of a lot of energy which would otherwise be raising the temperature of the water. Conversely, when freezing is taking place, the temperature will not go below zero until the freeze is complete.

Another effect is convection by wind, which transfers heat from warmer to colder places, and which makes surface temperature changes on Earth and on Venus rather smaller than they would otherwise be. There is less convection on Mars because of the thinner atmosphere.


http://en.wikipedia.org/wiki/Venus_(planet)
"Owing to the thermal inertia and convection of its dense atmosphere, the temperature does not vary significantly between the night and day sides of Venus despite its extremely slow rotation (less than one rotation per Venerean year; at the equator, Venus's surface rotates at a mere 6.5 km/h). Winds in the upper atmosphere circle the planet in only 4 days, helping to distribute the heat."

Note that thermal inertia and convection are not the same thing as the greenhouse effect. They keep surface temperature swings relatively small, but they have nothing to do with the very high average temperature on Venus.

Martin Gradwell


Posts: 323

Reply: 38



PostPosted: June 16, 2005 5:11 PM 

TR: Re: reply 35.

What I originally said was
"The amount of carbon dioxide is certainly not irrelevant. However, the thickness of the atmosphere is."

Now if we had, as "a planet that consisted of ten C02 molecules in its atmosphere. That's it: that's the entire atmosphere", then I think you will agree that the amount of carbon dioxide would be relevant. That, presumably, is why you stipulated it. And you couldn't have a planetary atmosphere consisting of just 10 atoms without that being a rather thin atmosphere - but the thinness of this atmosphere is purely incidental, and irrelevant to the fact that whatever greenhouse effect this atmosphere possesses depends solely upon the quantity of CO2 contained within it. You could even augment this atmosphere with enough non-greenhouse gas to give it a pressure and density ten times that of Earth's, and provided the added gas has absolutely no greenhouse effect whatsoever (and I don't know if in practice there is such a gas, but we are talking hypothetical situations here) then the entire high density atmosphere will exhibit just as much greenhouse effect as the ten CO2 atoms on their own.

They're Rocks


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Reply: 39



PostPosted: June 16, 2005 5:15 PM 

Martin, here's the point: an atmosophere consisting of 10 C02 molecules would have nogreenhouse impact -- obviously it would be too thin -- despite the fact that it would be 100 percent greenhouse-inducing. This is precisely why the thinness of the atmosphere matters.

They're Rocks


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Reply: 40



PostPosted: June 16, 2005 5:17 PM 

To be clearer in my last reply, when I said that the atmosphere would be "100 percent greenhouse-inducing," I simply meant that such an atmosphere would consist entirely of greenhouse gases. Obviously it would be too thin to induce any kind of greenhouse effect, however, and that was my whole point: The thickness of an atmosphere does indeed matter, when it comes to the greenhouse effect.

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