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Oliver
Thought Maker
Joined: 28 Feb 2004
Posts: 6096
Location: Antwerp, Belgium
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 Fri Mar 12, 2004 5:59 am Hot, hotter, hottest! |
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Hi,
I have a temperature question. I've posted it somewhere else but my question some how got lost. Here it is again:
| Oliver wrote: | | EnsignParis wrote: | | The surface of the photosphere (the surface of the sun) is only about 5000-6000 degrees celcius. However, the corona, which extends millions of miles out into space, can be exponentially hotter than the photosphere, ranging in millions of degrees at some points. |
So why is that? Pretend we're standing (or better floating) on the Sun's surface, the temp is about 5000-6000�C, but as we fly off in to space, it should get colder. Why is the corona hotter?
| Tiberius wrote: | The sun has an atmosphere, just like the Earth does, and the corona is the outer part of the sun's atmosphere. However, like the outer parts of Earth's atmospher, the Corona is vary rarified. The atoms in it are spaced very far apart. So while the temperature is very high, the actual heat is quite low.
It's a bit like how you can put your hand into a 200 degree oven and not get burnt, but you'll get badly scalded if you dip a finger into a cup of boiling water. Because the material inside the oven (air) isn't very dense, it doesn't transmit heat well, while the material inside the cup (water), being much denser, transmits the heat much better. |
I understand your explanation, but I don't understand something. You say that the corona's temp is graeter than the temp of the Sun's surface. Just like the temp in the oven is greater than that of a boiling cup. But when we put our finger in both of them, the cups 'feels' hotter.
So if we can't distinguish the real temp of something, how does a thermometer find out which is hotter. I mean, our sense of touch is sort of a thermometer (not an accurate one but still).
I hope you understand my question, it's hard to explain.
Oliver |
Last edited by Oliver on Tue Mar 16, 2004 11:11 am; edited 1 time in total
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webtaz99
Commodore
Joined: 13 Nov 2003
Posts: 1229
Location: The Other Side
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| Fri Mar 12, 2004 12:51 pm |
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Most of the material making up the corona was ejected from layers deeper in the sun. The surface layers are able to both "evaporate" and radiate heat into space, making them cooler. Also, coronal material is heated up by huge magnetic fields and high energy particles.
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"History is made at night! Character is who you are in the dark." (Lord John Whorfin)
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Dax Orien
Helmsman
Joined: 24 Aug 2001
Posts: 856
Location: My own little hell.
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| Tue Mar 23, 2004 8:52 am |
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Yeah that makes a lot of sense to me. The atmosphere of the sun would make leaving the photosphere and heading out to earth a little bit hotter. Heat is pretty much a stated and unchangable science. Pretty solid.
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"Let's all sing the 'Doom Song'!" ~~~ Gir
"Gir, it's been nice working with you, now self-destruct."
"FINALLY!"
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Oliver
Thought Maker
Joined: 28 Feb 2004
Posts: 6096
Location: Antwerp, Belgium
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| Fri Apr 09, 2004 9:34 am Re: Hot, hotter, hottest! |
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Let's say the temperaure in the oven is the same as the temperature of a cup of water, say 100�C. When we put our finger in both of them, the cups 'feels' hotter.
So if we can't distinguish the real temp of something, how does a thermometer find out which is hotter. I mean, our sense of touch is sort of a thermometer (not an accurate one but still).
P.S.: I've got a math quiz running in Fun & Games. I'm sure some of the posters here like to solve a math problem or two. Click here.
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webtaz99
Commodore
Joined: 13 Nov 2003
Posts: 1229
Location: The Other Side
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| Fri Apr 09, 2004 5:09 pm |
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First, there is a difference between heat and temperature. Heat is thermal energy, and every particle of mass can have its own amount of heat. Also, heat is transferred between particles by collisions and radiation. Temperature is a measure of the average thermal energy of a set of particles (or an object). Here's the kicker. Say you have two objects made of different materials at the same temperature. If you add (or subtract) the same amount of heat energy to/from both, they will end up with different temperatures!
Second, water transfers heat to a human body 20 times faster than air. That's why people who go scuba diving in 70F water get the chills. That's also why hot water "feels" hotter than hot air.
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"History is made at night! Character is who you are in the dark." (Lord John Whorfin)
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Oliver
Thought Maker
Joined: 28 Feb 2004
Posts: 6096
Location: Antwerp, Belgium
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| Sat Apr 10, 2004 1:03 am |
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Thanks for the quick respons but mi question isn't answered. I understand what you're saying but how a thermometer measure the correct temperature? Why doesn't it get fooled by the difference in density in materials just like we do
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webtaz99
Commodore
Joined: 13 Nov 2003
Posts: 1229
Location: The Other Side
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| Sat Apr 10, 2004 3:24 pm |
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| Oliver wrote: | | Thanks for the quick respons but mi question isn't answered. I understand what you're saying but how a thermometer measure the correct temperature? Why doesn't it get fooled by the difference in density in materials just like we do |
You can look at two things and say one is bigger, but you need a ruler (or other measuring device) to get the actual sizes. A thermometer is a device specifically designed and built to measure temperature.
Our sense of hot or cold is only meant to help us avoid getting hurt. It is not meant to allow us to accurately determine the temperature of things. If you watch weather reports you will see that the air pressure changes all the time, but we only sense very rapid changes in pressure. The slow changes don't pose a threat to our bodies.
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"History is made at night! Character is who you are in the dark." (Lord John Whorfin)
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Oliver
Thought Maker
Joined: 28 Feb 2004
Posts: 6096
Location: Antwerp, Belgium
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| Mon May 10, 2004 1:17 pm |
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Another temperature question: what's the average temperature of our entire universe?
All temperatures try to reach the average temperature. For instance, if you have a room where oe half is 10�C and the other half is 20�C, then eventually if you give it enough time, the room will be 15�C everywhere.
So, if we give our universe enough time, what temperature will it have. Since we have places in our universe of which it's temperature is greater than 0� Kelvin, the average temperature of our universe is larger than 0� Kelvin. But how much?
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webtaz99
Commodore
Joined: 13 Nov 2003
Posts: 1229
Location: The Other Side
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| Mon May 10, 2004 4:54 pm |
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It's kind of a trick question. Considering that the universe (as we know it) is more than 99% empty space, the average comes extremely close to absolute zero. The cosmic microwave background (radiation supposedly left over from the Big Bang) averages out at 2.275 Kelvin. As far as the universe reaching thermal equilibrium - we don't even know (and may never know!) if the universe is closed or open, and that makes a big difference.
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"History is made at night! Character is who you are in the dark." (Lord John Whorfin)
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Oliver
Thought Maker
Joined: 28 Feb 2004
Posts: 6096
Location: Antwerp, Belgium
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| Tue May 18, 2004 2:28 am |
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| In 'Space and nothing' on Sun Apr 25, 2004 9:29 pm, webtaz99 wrote: | | "Nothing" would have no temperature, only matter can have temp... |
...and over here you wrote:
| webtaz99 wrote: | | ...Considering that the universe (as we know it) is more than 99% empty space... |
Why do you have to consider empty space when measuring the average temperature as the temperature of empty space is undefined?
If we disregard empty space, as we should because "nothing" would have no temperature, the average temperature of our universe would be a lot greater...
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webtaz99
Commodore
Joined: 13 Nov 2003
Posts: 1229
Location: The Other Side
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| Thu May 20, 2004 6:20 pm |
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Like I said, it's a trick question.
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Oliver
Thought Maker
Joined: 28 Feb 2004
Posts: 6096
Location: Antwerp, Belgium
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| Mon May 24, 2004 1:18 pm |
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Hmm, I see.
So what is the answer?
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EnsignParis
Lieutenant Commander
Joined: 07 Sep 2001
Posts: 257
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| Thu May 27, 2004 9:46 am |
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Why do you expect us to know everything. Go look it up.
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Oliver
Thought Maker
Joined: 28 Feb 2004
Posts: 6096
Location: Antwerp, Belgium
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| Thu May 27, 2004 9:50 am |
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| EnsignParis wrote: | | Why do you expect us to know everything. Go look it up. |
I'm sorry you picked up my question that way. I don't expect you people to know everything. I was just re-opening this topic and asked my question in the hope that someone who does have an answer will let us know.
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"Oh God! I could be bound in a nutshell, and count myself a king of infinite space."
- Shakespeare, Hamlet
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Puck
The Texan
Joined: 05 Jan 2004
Posts: 5596
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| Fri May 28, 2004 12:04 am |
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Lol...well I certainly don't know....of course, tis very late and I am gettin very tired....that could have somethin to do with it. 
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EnsignParis
Lieutenant Commander
Joined: 07 Sep 2001
Posts: 257
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| Sun May 30, 2004 5:02 pm |
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| Oliver wrote: | | EnsignParis wrote: | | Why do you expect us to know everything. Go look it up. |
I'm sorry you picked up my question that way. I don't expect you people to know everything. I was just re-opening this topic and asked my question in the hope that someone who does have an answer will let us know. |
Hehe, ok
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superwoman
Vice Admiral
Joined: 25 May 2004
Posts: 5742
Location: Sweden
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| Fri Jun 04, 2004 2:53 pm |
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| Oliver wrote: | | Thanks for the quick respons but mi question isn't answered. I understand what you're saying but how a thermometer measure the correct temperature? Why doesn't it get fooled by the difference in density in materials just like we do |
The thermometer do too get fooled, but not as much as our body. The thermometer sensor is made of some sort of metal, and metal conduct heat good. Our body has insulation, and doesn't conduct heat very well.
If u put one hand in the owen and one in a cup of water (both lets say 50degres celsius), the water will feel warmer (becouse water, just lite metall, conduct heat better then air). But after a while they both will feel like the same temperature...
well ok?
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superwoman
Vice Admiral
Joined: 25 May 2004
Posts: 5742
Location: Sweden
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| Fri Jun 04, 2004 2:55 pm |
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| Oliver wrote: | | In 'Space and nothing' on Sun Apr 25, 2004 9:29 pm, webtaz99 wrote: | | "Nothing" would have no temperature, only matter can have temp... |
...and over here you wrote:
| webtaz99 wrote: | | ...Considering that the universe (as we know it) is more than 99% empty space... |
Why do you have to consider empty space when measuring the average temperature as the temperature of empty space is undefined?
If we disregard empty space, as we should because "nothing" would have no temperature, the average temperature of our universe would be a lot greater... |
HEY GUYS! If univers is 99% empty space, just count the 1%!
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EnsignParis
Lieutenant Commander
Joined: 07 Sep 2001
Posts: 257
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| Mon Jun 14, 2004 8:56 am |
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| superwoman wrote: |
The thermometer do too get fooled, but not as much as our body. The thermometer sensor is made of some sort of metal, and metal conduct heat good. Our body has insulation, and doesn't conduct heat very well.
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The metal, traditionally anyways, was mercury. As it heated up, it expanded upwards, representative of temperature changes as it climbed the thermometer.
At least I think.
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webtaz99
Commodore
Joined: 13 Nov 2003
Posts: 1229
Location: The Other Side
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| Thu Jul 01, 2004 4:44 pm |
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OK.
If we spread out the known matter in the universe so that it had a uniform density, it's temperature would be VERY COLD (close to 3 Kelvins).
If we take the average temperature of all the particles in the known universe, that would be VERY HOT (several million Kelvins).
It's a trick question. Take your pick.
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"History is made at night! Character is who you are in the dark." (Lord John Whorfin)
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