Waterworlds confirmed! [Archive] - Giant in the Playground Forums

Soras Teva Gee

2012-02-21, 10:17 PM

Technically we already have a waterworld within the solar system already and known about it a long time. No not Earth

Also this struck me as interesting:

Instead, the new observations reinforce the notion that GJ 1214b's atmosphere contains at least 50% water by mass. This, in turn, suggests that the planet's large size and modest density are due to large amounts of water in its interior, as opposed to a rocky world surrounded by a puffed-up blanket of hydrogen and helium.

The two emphasized bits are strike me as particularly bizarre. I keep trying to come up with a common analogy and I'm failing badly. However so help me it sounds like you could drown in this place's atmosphere.

Weezer

2012-02-21, 10:24 PM

This being in the media section the title made me think that a sequel to Waterworld had been announced. I couldn't tell if I was happy or terrified...

Traab

2012-02-21, 11:03 PM

Technically we already have a waterworld within the solar system already and known about it a long time. No not Earth

Also this struck me as interesting:

The two emphasized bits are strike me as particularly bizarre. I keep trying to come up with a common analogy and I'm failing badly. However so help me it sounds like you could drown in this place's atmosphere.

It sounds like a boiler. The water boils, rises as steam, then hits high enough in the atmosphere to turn back into water and fall again. Thats about the only way I can think of to describe an atmosphere that is 50% water. Its like being in a permanent waterfall.

Soras Teva Gee

2012-02-21, 11:27 PM

Traab you're close, but how to describe an apparent mixture of hot water and rock? I keep wanting to say dirty snowball, only really really hot.

zimmerwald1915

2012-02-21, 11:30 PM

Traab you're close, but how to describe an apparent mixture of hot water and rock? I keep wanting to say dirty snowball, only really really hot.
Precipitating slurryball?

An Enemy Spy

2012-02-22, 01:33 AM

Who's betting Jar Jar lives there?

Bastian Weaver

2012-02-22, 02:09 AM

Of course there's life somewhere out there. Universe is a big place, and Sun is, after all, a pretty usual star.

Feytalist

2012-02-22, 02:16 AM

It could simply mean that the interior of the planet is porous, with the water trapped within the rock, not necessarily "mixed-up".

TheSummoner

2012-02-22, 02:18 AM

Who's betting Jar Jar lives there?

We must destroy this planet. I don't care if it's only a chance, it isn't one I want to take.

Grinner

2012-02-22, 03:16 AM

Well, at any rate, it probably isn't exactly habitable. Unless....Kamino!

Parra

2012-02-22, 03:28 AM

It could simply mean that the interior of the planet is porous, with the water trapped within the rock, not necessarily "mixed-up".

So more of a Sponge World than a Water World?

Frozen_Feet

2012-02-22, 03:46 AM

Traab you're close, but how to describe an apparent mixture of hot water and rock? I keep wanting to say dirty snowball, only really really hot.

It sounds like a giant Sauna stove. Which means us Finns would likely do great there. :smalltongue:

Feytalist

2012-02-22, 03:55 AM

So more of a Sponge World than a Water World?

Sure, why not. And if the world is porous like that, it might even be able to warp out of shape and generate internal heat like Europa. That could be cool. Because heat + water = breeding grounds for life.

Eldan

2012-02-22, 06:44 AM

Technically we already have a waterworld within the solar system already and known about it a long time. No not Earth

Two, I thought, or are you not counting one of them?
Enceladus and Europa, is what I'm thinking of.

Cikomyr

2012-02-22, 07:22 AM

Radar

2012-02-22, 08:04 AM

Yhea, but Europa is a boring bit of ice. I don't wanna risk a repeat of Schwazenneger's Mr. Freeze.

I was thinking. Since this planet's main source of heat comes from solar radiation and not geothermal source, does it mean it's possible that the lower layers of water of the planets are less hot? Until you reach the lowest layers, obviously.
Not really - if all the surface is hot, then the interior will have to heat up as well. Otherwise we couldn't cook eggs.

Yes, if we start with an ice-cold planet, it would take some time to roast it over a red dwarf, but it's not like GJ 1214b got in it's orbit yesterday.

DigoDragon

2012-02-22, 08:19 AM

Finally! A water world without Kevin Costner! :smallbiggrin:
Boy, at the rate we're improving on finding more types of planets out there, I'm feeling pretty confident that we might find one that's broadcasting artificially created electromagnetic waves. Within my lifetime.
Alien MTV?

The only hard part then, is getting to any of these places within a resonable time frame.

However so help me it sounds like you could drown in this place's atmosphere.

I was thinking the same thing.

Sean Mirrsen

2012-02-22, 08:21 AM

Radar

2012-02-22, 09:15 AM

This depends on how much heat can water vapor radiate upon reaching the high point of the atmosphere on the planet's nightside. Remember, the planet is mostly boiling water. Evaporating water takes away heat, and if vapor precipitates on the nightside, there is a constant influx of low temperature water in the system. Depending on how intense the whole thing is, we may actually have a cooler layer somewhere within this sort of "hydrosphere", even if it exists only on the nightside. This layer will even be relatively static if the planet is tidal locked to the star. Damn, why does this thing have to be 40LY away! It'd be such an interesting planet to see. :smallfrown:
There are a few problems with this:
1. Water is a very strong greenhouse gas (when in gaseous form). An atmosphere practically saturated with water will keep the heat inside, which among other things mean, that the surface temperature would be more or less the same throughout the planet.
2. As evaporation takes energy, precipitation gives it away. The process, you are describing, is actualy helping even the temperature out.
3. Even tidal locking won't change much, as we can observe with Venus (technicaly not tidal locked, but close enough).

Cikomyr

2012-02-22, 09:35 AM

Finally! A water world without Kevin Costner! :smallbiggrin:
Boy, at the rate we're improving on finding more types of planets out there, I'm feeling pretty confident that we might find one that's broadcasting artificially created electromagnetic waves. Within my lifetime.
Alien MTV?

na-ah, no way. Bad idea. The last thing we want is to catch their TV broadcast with a 40-year delay. We'd look like the culturally retarded planet. Think of the people who arrives in the US and behave like Disco is still funky?!?

We have a standard to live up to. The only worst thing would be to be contacted by the local nerds with geeky math problems.

Sean Mirrsen

2012-02-22, 09:42 AM

I still like to think that the planet is tidal locked, and is in a state of balance. The star heats up one side of the planet's atmo/hydrosphere, and the other side radiates heat into space, creating eternal torrential rain on the nightside, and eternal boiling bubblebath on the dayside. The nightside would probably be just cool enough to be comfortable for life as we know it, considering water gets cool enough to precipitate at all.

At any rate, if water there was constantly kept above boiling point, wouldn't most of it eventually evaporate? The pressure would keep it down, but the atmosphere is still mostly water. No matter how slowly, the planet would've been losing mass to solar wind, especially this close to the star. It'd have to have been pretty darn huginormous to survive all this time.

Traab

2012-02-22, 09:52 AM

Well, at any rate, it probably isn't exactly habitable. Unless....Kamino!

Well, we would need protection from the temperature, and a method of extracting breathable air from the water thats everywhere. Those devices the cheddar monks used to swim to the gungan city might work. We should get some of them.

Eldan

2012-02-22, 11:18 AM

na-ah, no way. Bad idea. The last thing we want is to catch their TV broadcast with a 40-year delay. We'd look like the culturally retarded planet. Think of the people who arrives in the US and behave like Disco is still funky?!?

We have a standard to live up to. The only worst thing would be to be contacted by the local nerds with geeky math problems.

Ah, but...
By the time they'd hear us liking their culture from 40 years ago, 80 years would have passed and we'd be enormously retro-chique.
Steampunk, anyone?

Grinner

2012-02-22, 11:49 AM

Well, we would need protection from the temperature, and a method of extracting breathable air from the water thats everywhere. Those devices the cheddar monks used to swim to the gungan city might work. We should get some of them.

When I wrote that, I had been thinking of something closer to an underwater sea lab, but the previous mention of Jar Jar made a Star Wars reference sound better.

Edit: But what if something breaks? :smalleek:

Soras Teva Gee

2012-02-22, 12:23 PM

Two, I thought, or are you not counting one of them?
Enceladus and Europa, is what I'm thinking of.

Europa was the one I was thinking of. I don't hear as much about Enceladus and its seems scientists are less sure of what exactly is going on there. Europa though gets fairly generally stated has having a liquid water under the ice.

At any rate, if water there was constantly kept above boiling point, wouldn't most of it eventually evaporate? The pressure would keep it down, but the atmosphere is still mostly water. No matter how slowly, the planet would've been losing mass to solar wind, especially this close to the star. It'd have to have been pretty darn huginormous to survive all this time.

I don't think evaporation does what you think it does. It covers a transition from liquid to gaseous states, diffusion into space is going to be something different. Also at 50% of the atmosphere liquid water is going to be pretty slow to evaporate.

Also this planet is much more massive then Earth, so a higher gravity. Also at the same time its star is much much lower energy. And finally it might have a powerful enough magnetic field to shield it, that's not something covered by this study.

I likewise don't know that what you'd suggest would help all that much.

Radar

2012-02-22, 12:29 PM

Ah, but...
By the time they'd hear us liking their culture from 40 years ago, 80 years would have passed and we'd be enormously retro-chique.
Steampunk, anyone?
You could also pick up newer transmissions on the way there. If they are even remotely similar to us, you could also mix things up however you like (including mismatched clothing and the like) and pretend it's too deep and complicated to explain. :smallwink:

Nerd-o-rama

2012-02-22, 12:30 PM

We have a standard to live up to. The only worst thing would be to be contacted by the local nerds with geeky math problems.

Like we were in Contact?

Cikomyr

2012-02-22, 12:42 PM

Like we were in Contact?

Precisely (http://www.theonion.com/articles/earth-contacted-by-extraterrestrial-nerds,1044/)

Eldan

2012-02-22, 01:57 PM

Like we were in Contact?

Like the stuff we are already sending out.

Soralin

2012-02-22, 02:47 PM

At any rate, if water there was constantly kept above boiling point, wouldn't most of it eventually evaporate? The pressure would keep it down, but the atmosphere is still mostly water. No matter how slowly, the planet would've been losing mass to solar wind, especially this close to the star. It'd have to have been pretty darn huginormous to survive all this time.
It's thought that something just like what you describe happened to Venus in the past. That at one time, briefly, Venus had oceans, which evaporated, and the water eventually got split apart, and the hydrogen lost to the solar wind (Since, it's much lighter, and easier to impart enough energy to it to knock it out of Venus' gravitational well.)

So basically, Venus' ultra-thick atmosphere is primarily what's left over of it's oceans. :)

Knaight

2012-02-22, 05:03 PM

Not really - if all the surface is hot, then the interior will have to heat up as well. Otherwise we couldn't cook eggs.

Variable temperature on planets is well documented. Regarding this particular planet, we can take a few things into account.
1) Much of the heat is not going into temperature increase, but into phase change from liquid water to steam. That requires a rather inordinate amount of heat, and the specific heat of steam is also very high.
2) We know that steam radiates some amount of heat, and as such some amount of heat is released by the planet. That means that it could effectively be in equilibrium.
3) There is a connection between heat and density, and low density fluids tend to rise. As such, hot water will rise towards the top, as will hot steam. This effectively guarantees layers of variable temperature.

The short version: Yes, heat will gradually transfer through the planet. That doesn't mean that it won't be counteracted by the hot water moving towards the surface, the huge amount of energy going into boiling water, and the release of energy from radiation back into space.

Now, onto other things. We know that water is a greenhouse gas, but we also know that clouds have an effect on a planet's albedo. Anyone have any hypotheses?

Traab

2012-02-22, 05:22 PM

When I wrote that, I had been thinking of something closer to an underwater sea lab, but the previous mention of Jar Jar made a Star Wars reference sound better.

Edit: But what if something breaks? :smalleek:

Same thing that happens in any scenario where the equipment we rely upon to keep us alive breaks. We die.

Radar

2012-02-23, 01:58 PM

Variable temperature on planets is well documented. Regarding this particular planet, we can take a few things into account.
1) Much of the heat is not going into temperature increase, but into phase change from liquid water to steam. That requires a rather inordinate amount of heat, and the specific heat of steam is also very high.
2) We know that steam radiates some amount of heat, and as such some amount of heat is released by the planet. That means that it could effectively be in equilibrium.
The planet is most definitely in equilibrium - it is way too old not to be. A black body at 500K radiates 3,5kW per m^2 - that's not much considering the size of the whole planet and specific heat of water in liquid and gaseous form. I would venture a guess, that in such a situation, we can easily approximate the planet as a closed system. Considering that radiation is the only process allowing heat dissipation here, ammount of heat taken by boiling water in an equilibrium state is restricted by the ammount of heat, that can be radiated away, since the vapour has to be able to emit all that heat in order to condensate. Even worse, at higher altitudes the temperature would have to be significantly lower to provide water condensation due to much lower preassure.

3) There is a connection between heat and density, and low density fluids tend to rise. As such, hot water will rise towards the top, as will hot steam. This effectively guarantees layers of variable temperature.
That is true, but only when you start with low density fluid below the high density one. Diffusion will take place anyway and even out the differences. A sample experiment could be made with a thermos: pour in cold liquid first (let's say water) and warmer liquid with lower density on top of it (like vegetable oil) - the temperatures will even out even if the liquids don't mix. The only technical problem is, you would need a thermocouple to make the measurments.

Even if I'm wrong here, processes you describe can't lower the temperature of planet's surface below water's boiling point at the prevailant atmosphere preassure, which will most likely be higher then ours.

t209

2012-02-23, 03:55 PM

Is the planet's water drinkable? Just asking since we need a fresh, non toxic water if we want to live on this planet.

Knaight

2012-02-23, 07:10 PM

The planet is most definitely in equilibrium - it is way too old not to be. A black body at 500K radiates 3,5kW per m^2 - that's not much considering the size of the whole planet and specific heat of water in liquid and gaseous form. I would venture a guess, that in such a situation, we can easily approximate the planet as a closed system. Considering that radiation is the only process allowing heat dissipation here, ammount of heat taken by boiling water in an equilibrium state is restricted by the ammount of heat, that can be radiated away, since the vapour has to be able to emit all that heat in order to condensate. Even worse, at higher altitudes the temperature would have to be significantly lower to provide water condensation due to much lower preassure.
My thoughts exactly.

That is true, but only when you start with low density fluid below the high density one. Diffusion will take place anyway and even out the differences. A sample experiment could be made with a thermos: pour in cold liquid first (let's say water) and warmer liquid with lower density on top of it (like vegetable oil) - the temperatures will even out even if the liquids don't mix. The only technical problem is, you would need a thermocouple to make the measurments.
A thermos isn't nearly large enough, nor nearly exposed to continual heat enough for this to be comparable at all. That said, look at Earth's oceans - they get colder as they get deeper, with obvious exceptions at volcanic vents.

Even if I'm wrong here, processes you describe can't lower the temperature of planet's surface below water's boiling point at the prevailant atmosphere preassure, which will most likely be higher then ours.
It will almost certainly be higher than ours - the planet has significantly higher gravity, and is dealing with less in the way of solar wind. As such, the surface should be at about boiling point. With that said, water not on the surface can be well under the boiling point, which is the point.

Radar

2012-02-24, 03:49 AM

A thermos isn't nearly large enough, nor nearly exposed to continual heat enough for this to be comparable at all. That said, look at Earth's oceans - they get colder as they get deeper, with obvious exceptions at volcanic vents.
Smaller scale only means, you get to observe the processes involved in a reasonable time. Exposure to continual heat can very well be added to the system, but as was said, it's insignificant. Besides, temperature gradient inversion will only be observed before achieving equilibrium.
As for Earth's oceans, it only applies to roughly half of our oceans, if you look nearer to the poles, it's the other way around. In short, oceans near the equator can have temperature gradient inversion, because the heat can be dumped near the poles. With a thick cloud blanket this won't be the case.

It will almost certainly be higher than ours - the planet has significantly higher gravity, and is dealing with less in the way of solar wind. As such, the surface should be at about boiling point. With that said, water not on the surface can be well under the boiling point, which is the point.
The problem is, it can't be of lower temperature - if the whole surface is at boiling point, then anything lower then that will be heated through heat-conduction and diffusion with no means of dissipating the heat - it could only go to a place with even lower temperature and there's none of that, if your surrounded by a heater. If anything like that was ever possible, we could build refrigerators working with no power used.

Sean Mirrsen

2012-02-24, 06:06 AM

Smaller scale only means, you get to observe the processes involved in a reasonable time. Exposure to continual heat can very well be added to the system, but as was said, it's insignificant. Besides, temperature gradient inversion will only be observed before achieving equilibrium.
As for Earth's oceans, it only applies to roughly half of our oceans, if you look nearer to the poles, it's the other way around. In short, oceans near the equator can have temperature gradient inversion, because the heat can be dumped near the poles. With a thick cloud blanket this won't be the case.

The problem is, it can't be of lower temperature - if the whole surface is at boiling point, then anything lower then that will be heated through heat-conduction and diffusion with no means of dissipating the heat - it could only go to a place with even lower temperature and there's none of that, if your surrounded by a heater. If anything like that was ever possible, we could build refrigerators working with no power used.Refrigerators work by taking heat away by cooling a conducting agent, and cooling the agent by radiating heat into the atmosphere. In this case, the cooling agent is water, the radiator is the planet's atmo/hydrosphere filled with hot water vapor, and the atmosphere's role is confusingly played by the cold blackness of space, which isn't actually cold but is a good outlet for radiant heat. With steam reflecting heat from the dayside, and radiating away heat from the nightside, I'd guess that even if the surface temperature of the planet is above boiling point, it's definitely cooler further down, and moreso on the nightside, especially if the planet's tidal locked. Depending on how well the heat is radiated away, there can even be areas where humans could survive.. well, in deep diving gear, at least. Increased gravity plus ridiculous water content... the pressure on the surface would probably be pretty high.

I can't help but wonder how the heat transfer actually occurs on this planet. Let's presume it's tidal locked, so we can treat it as a static ball with a static-ish heat source next to it. At 1.something million kilometers (IIRC), even a red dwarf is pretty huge, so the "dayside" is bigger than the "nightside" by a large margin, creating a comparatively small area where heat radiated away will be greater than heat received from the star. So, most of the planet's cooling is centered in one comparatiely small spot, creating a massive pressure sink, as the hot air/water mix rises to be cooled, and drops one it condenses. So, huge rainy storm cell with gigantic hurricanes, pretty much permanent and static on one side of the planet. Where does the heat (or rather, lack of it) go from there? I wonder, if the planet's rock core is porous enough to allow water to pass directly through it (well, not through the core itself likely), would the density difference between above-boiling-point high-pressure water and below-boiling-point somewhat-cool water, be enough to actually create a sub-surface current? Because that'd be cool. :) Also, my knowledge on this is obviously insufficient (the above is mostly verisimilitude, me extrapolating known data based on my understanding of the concepts), but would the proximity to the star actually affect the water, giving it an additional "pull"? So that the cold water would flow towards the dayside not just because of pressure difference, but also due to density difference, i.e. being "heavier" than hot water?

Radar

2012-02-24, 06:28 AM

Refrigerators work by taking heat away by cooling a conducting agent, and cooling the agent by radiating heat into the atmosphere. In this case, the cooling agent is water, the radiator is the planet's atmo/hydrosphere filled with hot water vapor, and the atmosphere's role is confusingly played by the cold blackness of space, which isn't actually cold but is a good outlet for radiant heat. With steam reflecting heat from the dayside, and radiating away heat from the nightside, I'd guess that even if the surface temperature of the planet is above boiling point, it's definitely cooler further down, and moreso on the nightside, especially if the planet's tidal locked. Depending on how well the heat is radiated away, there can even be areas where humans could survive.. well, in deep diving gear, at least. Increased gravity plus ridiculous water content... the pressure on the surface would probably be pretty high. (...)
Refrigerator works, because we forcefuly compress the coolant to rise it's temperature above the surrounding in order to dissipate the heat and then decompress it adiabaticaly to lower it's temperature below the one we try to keep inside - the whole process needs outside source of low-entropy energy and can't occur spontaneously. That's the most basic fact about thermodynamics.

(...) Also, my knowledge on this is obviously insufficient (the above is mostly verisimilitude, me extrapolating known data based on my understanding of the concepts), but would the proximity to the star actually affect the water, giving it an additional "pull"? So that the cold water would flow towards the dayside not just because of pressure difference, but also due to density difference, i.e. being "heavier" than hot water?
Nope, just regular symmetric tides.

Sean Mirrsen

2012-02-24, 07:20 AM

Refrigerator works, because we forcefuly compress the coolant to rise it's temperature above the surrounding in order to dissipate the heat and then decompress it adiabaticaly to lower it's temperature below the one we try to keep inside - the whole process needs outside source of low-entropy energy and can't occur spontaneously. That's the most basic fact about thermodynamics.Er, quite. I have little insight on the actual mechanics of a refrigerator, but that still means we transfer heat to a conducting agent, and have the heat radiated away. If the refrigerator didn't radiate heat, it'd continuously gain energy from its own operation, and even though it'd probably succeed at keeping the cold inside, that would only be until its components failed from the heat buildup. In other words, a planet is not a closed system. It cannot conduct away heat like a refrigerator's radiator does, but it sinks heat by radiating it into space. Whatever cooling equipment exists on the space station probably has to work the same way for instance, unless they depend on pre-cooled agent shipments.

Nope, just regular symmetric tides. Oh well. :) Still, such a pity this thing is so far away. Quite an interesting planet. All we got here are some humongous gasballs, and a collection of rocks at varying degrees of being fried and frozen. Plus Earth.

DigoDragon

2012-02-24, 07:38 AM

Like the stuff we are already sending out.

I'm reminded of the episode of Futurama where an alien race invades Earth demanding to see the final episode of an old Earth broadcast from 1000 years ago. :smallsmile:

Radar

2012-02-24, 08:15 AM

Er, quite. I have little insight on the actual mechanics of a refrigerator, but that still means we transfer heat to a conducting agent, and have the heat radiated away. If the refrigerator didn't radiate heat, it'd continuously gain energy from its own operation, and even though it'd probably succeed at keeping the cold inside, that would only be until its components failed from the heat buildup. In other words, a planet is not a closed system. It cannot conduct away heat like a refrigerator's radiator does, but it sinks heat by radiating it into space. Whatever cooling equipment exists on the space station probably has to work the same way for instance, unless they depend on pre-cooled agent shipments.
Yes the planet does radiate the heat away at more or less the same rate it absorbs it from it's sun. The thing is, it is insignificant in comparison to internal heat transfer and won't in any case create an inverse temperature gradient.
My point was, you can't have a cyclic reaction (as in: without causing any permanent changes), that creates a temperature difference in the system.

Sean Mirrsen

2012-02-24, 09:01 AM

Yes the planet does radiate the heat away at more or less the same rate it absorbs it from it's sun. The thing is, it is insignificant in comparison to internal heat transfer and won't in any case create an inverse temperature gradient.
My point was, you can't have a cyclic reaction (as in: without causing any permanent changes), that creates a temperature difference in the system.A planet that's mostly water would not be able to exist this close to a star for this long if it didn't balance the heat gained from the star with some means of heat loss. Even Earth has to lose its heat to something.

(pause for quick wiki-walk)

Mmkay, I seem to be talking about some twisted application of a zero-dimensional climate model. Basically, if the planet is effectively static, the temperature differentials become constant. One, bigger, half of it is consistently hot, the other is consistently comparatively cool. This will naturally create a thermal inversion scenario, as the nightside cooling air and water will constantly flow under the hot air and water from the steaming hot dayside. This effect will never be noticeable on a non-tidal-locked planet, which is probably why it's not observed anywhere in our solar system. It requires a solid planet with an atmosphere that's 1:1 tidal locked to the star. Mercury is tidal locked 2:3 or something, and its atmosphere is too thin to observe. Venus and Mars aren't locked, and everything past Jupiter is either a humongous ball of opaque gas or too far to be heated in any meaningful way by the Sun.

(Also, static system with cyclic effects on temperature differences? Why am I reminded of a lava lamp?)

Hm, by the way. What if the planet is not rock, but metal? Since it's still water, if the measurements at this distance can be believed on that, then something is preventing it from doing like Venus and upgrading the water to sulfuric acid, or something else. What if it has a magnetic field? Can it be a spinning metal ball surrounded by a mass of water?
(Yes, I am aware that's a rather unlikely scenario. I just like throwing out random ideas to see if anything connects. :) )

Soralin

2012-02-24, 11:55 AM

If a tide-locked planet is at the right temperature to have liquid oceans over a lot of it's surface, you could end up with something like a heat-pipe. Water gets evaporated on the day side, and flows towards the night side, where it precipitates out into the ocean, and flows back towards the day side.

So, you end up with hot moist air continuously flowing from the day side to the night side, and cold water continuously flowing from the night side to the day side, keeping temperatures more temperate than you might expect.

Although this planet might be a bit too hot, with too much boiled away for that to work in this case.

Radar

2012-02-24, 12:03 PM

A planet that's mostly water would not be able to exist this close to a star for this long if it didn't balance the heat gained from the star with some means of heat loss. Even Earth has to lose its heat to something.
I stated quite clearly, that radiation compensates the energy absorbed from the star. Considering that the atmosphere is quite saturated with water, even tidal lock won't create significant temperature differences in such a case.

Mmkay, I seem to be talking about some twisted application of a zero-dimensional climate model. Basically, if the planet is effectively static, the temperature differentials become constant. One, bigger, half of it is consistently hot, the other is consistently comparatively cool. This will naturally create a thermal inversion scenario, as the nightside cooling air and water will constantly flow under the hot air and water from the steaming hot dayside. This effect will never be noticeable on a non-tidal-locked planet, which is probably why it's not observed anywhere in our solar system. It requires a solid planet with an atmosphere that's 1:1 tidal locked to the star. Mercury is tidal locked 2:3 or something, and its atmosphere is too thin to observe. Venus and Mars aren't locked, and everything past Jupiter is either a humongous ball of opaque gas or too far to be heated in any meaningful way by the Sun.
To make things clear I'd probably have to run some numbers, but I doubt, that convection would be the deciding factor - especially considering, that both heater and heat sink are on the outside of the planet.

(Also, static system with cyclic effects on temperature differences? Why am I reminded of a lava lamp?)
Because there would be no noticable convection, if you put the lightbulb on the top? :smalltongue:

Anyway, we got bogged down in details and it all started with a question on habitable areas on this planet. For all we know the stated temperature (a few hundreds degrees above water's boiling point in normal preassure) is an estimated average temperature. So for an area with temperatures around 300K, we would need a day/night difference of at least 500K-600K. You can find such differences on Mercury, but on a planet with thick and fairly opaque (considering the ammount of water there) atmosphere it's more then unlikely.