PDA

View Full Version : Planet climates



m1omg
2007-Oct-13, 07:43 PM
I am curious;
1.How far from the Sun would an Earth-mass and composition and geologically active, with a some sort of seasons, glaciated on almost all the surface with a liquid ocean only somewhere between the Tropic of Cancer and Tropic of Capricorn have to be (assuming an atmosphere similar to Earth's)?I mean, planet like those "ice planets" in scifi; like Hoth (Star Wars) or Sigma Draconis IV (Westwood Dune games).And would the lack of almost any multicellular plants except maybe some cold enduring small plants near the Equator create an atmosphere poorer in oxygen than ours?What would be an [B]average[B][/sB] temperature of that planet?And what about polar and equatorial temperature?

2.How much warm could be an Earthlike planet be without going severe wet greenhouse (like To'uhl in OA) or runaway greenhouse (like Venus)?

3.Could a period of very massive volcanic or impact caused outgassing create a catastrophical runaway greenhouse effect after the soot will fell down?

4.What kinds of life may develop on a carbon planet with some water in the "temperate zone"?I have read here; http://en.wikipedia.org/wiki/Carbon_planet ; that the organisms living on such a planet would eat oxygen containing things as food and "breathe" the carbon containing atmosphere, how would such a planet appear?Will the seas consist of water under a bubbly layer of oil and hydrocarbons?What would be the atmosphere composed of?

Ronald Brak
2007-Oct-14, 06:16 AM
NOTE: I did a quick google on this for you and immediantly ran into stuff that was just plain wrong, but if you think through stuff carefully and relate it back to real examples you should be okay and able to seperate fact from fiction. What I've written may not be right, but at least it will be more right than some people.


1.How far from the Sun would an Earth-mass and composition and geologically active, with a some sort of seasons, glaciated on almost all the surface with a liquid ocean only somewhere between the Tropic of Cancer and Tropic of Capricorn have to be (assuming an atmosphere similar to Earth's)?

If you moved the earth back to where mars is then it then very quicky the average world temperature would drop to well below freezing, not only because of the further distance from the sun but also because spreading ice would reflect more heat and water vapour, the greenhouse gas with the largest effect would be frozen out. So the earth would be frozen all over. But then, very slowly, volcanoes would add CO2 to the atmosphere and the earth's temperatures would rise until there was liquid water at the equator. Now it might snowball up again as photosynthetic life starts to absorb CO2, or some sort of equilbrium might be reached with a cooler but habitable earth with, very roughly, CO2 levels over 1%.


2.How much warm could be an Earthlike planet be without going severe wet greenhouse (like To'uhl in OA) or runaway greenhouse (like Venus)?

I don't know, but earth can supposedly be moved close to the orbit of venus before it has a runaway greenhouse effect. As the earth is moved closer to the sun, increased levels of water vapour makes things stinking hot, but increased cloud cover tends to counter act this while increased rainfall and weathering of rocks tend to remove CO2 causing its concentration to drop. The biosphere may also be able to absorb more carbon.


3.Could a period of very massive volcanic or impact caused outgassing create a catastrophical runaway greenhouse effect after the soot will fell down?

I don't think that would be a real possibility. We've had big impacts and supervolcanoes in the past that haven't had that effect, and the earth is supposed to be pretty resistant to a runaway greenhouse effect in the first place.


4.What kinds of life may develop on a carbon planet with some water in the "temperate zone"?

Gah!

John Mendenhall
2007-Oct-16, 09:37 PM
4.What kinds of life may develop on a carbon planet with some water in the "temperate zone"?I have read here; http://en.wikipedia.org/wiki/Carbon_planet ; that the organisms living on such a planet would eat oxygen containing things as food and "breathe" the carbon containing atmosphere, how would such a planet appear?Will the seas consist of water under a bubbly layer of oil and hydrocarbons?What would be the atmosphere composed of?

Don't know. Let's drag Titan into an Earth-Sun Trojan point and see what happens.

Warren Platts
2007-Oct-17, 09:40 AM
See Leger et al. (2003) A new family of planets? "Ocean Planets" (can be found in Astro-ph (arXiv.org)):


The interest of such planets is at least double, for Planetology and Exobiology. They would be a kind of objects we have not in the Solar System and significantly extend the field of Planetology. The search for a form of life similar to that which has developed on Earth would open a new field in Exobiology because the conditions of the environment would be quite different from the terrestrial ones. The minerals necessary to living bodies (P, S, Fe, Mg, Na, Ků) could be brought to the surface by micro-meteorites or found in the ocean as dissolved species. It could even tell us something about origin of life on Earth e.g. by excluding an origin from black smokers at the silicate/ocean interface because on Ocean-Planets, liquidwater and silicates would be separated by thousands of kilometres of ice.

m1omg
2007-Oct-21, 06:42 PM
NOTE: I did a quick google on this for you and immediantly ran into stuff that was just plain wrong, but if you think through stuff carefully and relate it back to real examples you should be okay and able to seperate fact from fiction. What I've written may not be right, but at least it will be more right than some people.



If you moved the earth back to where mars is then it then very quicky the average world temperature would drop to well below freezing, not only because of the further distance from the sun but also because spreading ice would reflect more heat and water vapour, the greenhouse gas with the largest effect would be frozen out. So the earth would be frozen all over. But then, very slowly, volcanoes would add CO2 to the atmosphere and the earth's temperatures would rise until there was liquid water at the equator. Now it might snowball up again as photosynthetic life starts to absorb CO2, or some sort of equilbrium might be reached with a cooler but habitable earth with, very roughly, CO2 levels over 1%.



I don't know, but earth can supposedly be moved close to the orbit of venus before it has a runaway greenhouse effect. As the earth is moved closer to the sun, increased levels of water vapour makes things stinking hot, but increased cloud cover tends to counter act this while increased rainfall and weathering of rocks tend to remove CO2 causing its concentration to drop. The biosphere may also be able to absorb more carbon.



I don't think that would be a real possibility. We've had big impacts and supervolcanoes in the past that haven't had that effect, and the earth is supposed to be pretty resistant to a runaway greenhouse effect in the first place.



Gah!


I don't mean tiny events like supervolcanos and KT events, but BIG ones like 100 km iron asteroid impact.

astromark
2007-Oct-22, 12:56 AM
There is a much talked about web address 'Earth Impacts' (or something like that) Will find it...
In that program a large enough and fast enough impactor could destroy the planet. Reducing it to a asteroid belt. That has little to do with your question other than the fact that all things are relative.
Earth has a slightly ellipse orbital path. The amount of energy received will obviously drop by the inverse law as the planets distance from the sun grew greater. Any reduction in solar energy would change the climate. Just a little change could be a Ice age event. As Ronald said. A chain of events would change things. More polar ice would reflect away more heat. Some life forms could adapt. Mars distance from the sun might be at the outer edge of possible.
Just as an aside here. What if the rotational speed was less. Would the sun then have time to warm the planets biosphere.? Or would little advantage be available as the nights would be longer by as much...

The point I see as worthy of mention is this; Life has prov-en by several extinction events past, to be tenacious. If it can it will. It may look very different. It might be very different. But it would still be life.
The number of events from Earths past that have changed the rules for survival are many.
Do not think that this planet has just the right recipe for life. Instead I word it as, Life here has evolved to best survive in this environment. It does not need to be this way.

neilzero
2007-Oct-22, 07:37 AM
If Earth was in a circular orbit 120 million miles from the sun, instead of 92 million miles, galciers would cover all but the tropic zone, and the tropics would also freeze if the green house gases in the atmosphere decreased. Green house gases would likely be sequestered as a result of the low average temperature, so perhaps 100 million miles is farthest to avoid the worst ice age Earth has had so far. Since most of the creatures who breath oxygen would be dead, the oxygen in the atmosphere would likely decrease about 1% per 1000 years to about 11% in 10,000 years. It might take a million years to decrease to 1% oxygen. Average polar temperature would be about minus 200 degrees f. Average equatorial temperature about 40 degrees f.
A large increase in green house gas might allow present glaciers at 125 million miles from the sun.
2 My guess is Earth's average temperature could increase from the present 60 degrees f to 120 degrees f, before we would be in serious runaway green house warming. I'll guess 85 million miles from the sun in circular orbit would cause the Earth's average temperature to stabilize at 120 degrees f.
If we had the technology to remove significant green house gases from the atmosphere, Earth would likely stabilize at 110 degrees f in circular orbit 85 million miles from the Sun.
3 Very massive volcanos might eventually melt 99% of the present ice, but the outgasing would have to persist for thousands of years, or the glaciers would begin to reform, It is hard to imagine how we could have volcanos spewing green house gas without spewing particulates which cool the Earth.
4 I read about the carbon planet in wikipedia, but I have no idea about life forms which might live on such a planet. Neil