Welcome Guest [Log In] [Register]
Sky Dragon is up and running. We need people to sign up and add content. Introduce yourself at the General discussion forum. Speak up to welcome a few others, start a thread, or contribute to someone else's thread.
Viewing Single Post From: The giant space ship example

Chris Ho-Stuart
Dec 5 2011, 02:22 AM
Gbaikie, I have added quote tags to your post just above, which is the usual way to quote from a previous post. You can edit your own post again to have a look at how it works.

When you enter the text, it looks like this:

[Quote=NameOfMember]This is the text from a member.[/Quote]
This is your reply

While you are entering your post, there is a row of buttons above the box where you enter text. These can add formatting to your post; it will appear as "BBCode tags", which are in square brackets. One of the formatting buttons is marked "Quote", which added anonymous quote tags (no name supplied).


As for your questions, they all relate to the different between how long it takes to heat up by a certain amount; and how far you can heat up.

When you add a new supply of energy to the surface, it does not keep warming indefinitely. It only warms up until the thermal radiation emitted is once again equal to total energy being supplied. I have ignored how long it takes to warm up, and considered only how far it will warm up.

yes I know- warmer it become more heat loss.
But with just 10 K increase it wouldn't that significant.

I will illustrate what I mean. Suppose we cover the planet in 2 meters water and freeze it so it's ice at 2 K.
With this done, I can add the 150 K air. And heat the air with these 6,580,000 GigaWatts reactors.
The ice I am not trying to directly heat, and I could basically ignore it. Because the air will take "forever" to warm it.
But the time it takes to warm the air will inform you about how much energy is needed.

Not really. The time it takes to warm the air informs you about how much heat capacity there is.

In the case of Nitrogen/Oxygen mix, really the only way you can heat the air is by putting the air in physical contact with a hot plate of some kind. That's exactly the same as putting in physical contact with a layer of ice.

By the way... water becomes ice at a temperature of 273 K. This is an absolute temperature scale. So water at 2 K is going to be so cold that it will freeze the air itself!

Yeah, would it cause nitrogen liquidity or snow.
Also pretty hard to cool it to 2 K. Whereas 150 K would be quite easy, 150 being temperature water ice stops evaporating in vacuum.

The final temperature of anything is the temperature at which it is no longer gaining thermal energy at all.

I recommend you don't worry about how long it takes to heat up and cool down. Perhaps we could make a new thread on thermodynamics in general for such questions. The question originally posed is about the power required to maintain a certain temperature in the starship. That is adding energy to make up for energy being lost as the starship radiates thermally to space.

yeah that would be good.

Now, it seems the most significant element is average atmosphere temperature- rather than ground temperature or surface air temperature.
And next second important element would significant air mass "bordering/closest" to vacuum of space. And this second element I have no clue how to quantify.
So if second important element is not significant or could reduced somehow, then isn't first element to main factor in determining heat loss from atmosphere?
Edited by gbaikie, Dec 5 2011, 06:38 AM.
Offline Profile Quote Post
The giant space ship example · Physical theory for climate