Global Warming?

[f95toli]

Reflected IR==reflected heat.
Read the text you linked to.

But yes, the reduced convection also plays a role (no wind).
Conduction does not play any role in an ordinary glass house, basically the only way to reduce conduction through air is to use a vacuum; you can e.g. use two layers of glass and pump a vacuum inbetween; this is how a thermos bottle works.

I work in the field of low-temperature physics and sometimes I use glass cryostats, so I am well aware of how heat is transmitted in this case.

I am not sure what you are asking for. Are you looking for a link to a site showing the spectra of CO2?
Try
http://chemistry.beloit.edu/Warming/

(look for "infrared spectra of Greenhouse gases")

 

[chcarnage]

Originally posted by: Noworkia
How does carbon dioxide trap heat? Does anyone have a link to a model or experiment showing the process on a small scale?

It doesn't "trap" heat in the form of preventing it from leaving the earth, it absorps solar radiation of a certain wavelength and gets warmer. According to this calculation based on quantum mechanics, CO2 currently is responsible for up to 12% of the greenhouse effect.

http://en.wikipedia.org/wiki/Greenhouse_effect#Effects_of_various_gases

It's also known that the present CO2 concentration in the athmosphere increased 40% since the beginning of the industrialisation...

http://en.wikipedia.org/wiki/Carbon_dioxide#Atmosphere

...and that the concentration is higher than it was at every point in the last 400'000 years.

http://en.wikipedia.org/wiki/Carbon_dioxide#Variation_in_the_past

Originally posted by: Calin

Originally posted by: Vee
The reason Mars and Venus are sterile and unhabitable, is not really for certain due to the difference in distance to the sun compared to Earth. It is due to the makeup of their atmospheres.

I don't really agree about that. A Earth-like planet at the distance where Mars is will have survivable temperatures, but I really don't think it will have any spot warmer than freezing point, making sustainability difficult at best.
And at Venus' distance, I really think it would be too hot (but I don't know for sure).

I thought about summer/winter temperature differences at 45 latitude but this would be wrong. I would like to have some data of temperatures around equator in summer/winter, showing differences for the 3.4% difference in distance to Sun

I think you're right about Mars because he has much CO2, but a very thin athmosphere. Venus on the other hand has a thick CO2 athmosphere and is hotter than Mercury, thanks to the greenhouse effect.

The poles and the equator don't have different temperatures because of the different distance to the sun (the difference is much smaller than 3,4%). The average angle sunrays have when they hit the surface (and therefore a different quantity of sunrays per square meter) causes it.

Originally posted by: deepred98

Homo Sapiens has been around for at least 160 000 years, probably somewhat longer (200 000-400 000 years)

uh i said documented as in people actually writing down stuff
not half monkeys that i really don't consider human

and uh our climate hasn't really changed that much right now
it has gotten warmer by at most a couple degrees celcius which i really don't think is that much and anyways during the ice age temperatures dropped a lot more then that even if it were over a longer period of time so don't you think maybe this is just earth's way of balancing out the ice age
and anyway new research shows taht earth's magnetic field has switched poles quite a few times already and these switches happended over about a century you may think this has nothing to do with global warming but doesn't that just show that earth really isn't that predictable.

We have methods to gain information from the past, for example enclosed air in ice up to 420'000 years old.

And every degree the world climate changes influences the weather in delicate zones, flat islands risk to lose area, the continent heats up quicker than the oceans, and many ecosystems face changes and problems. Ice Ages weren't a piece of cake scenario.

Plus the consequences of human influences on the athmosphere manifest with a big delay so it's not okay to do nothing as long as you judge the climate change to be tolerable. It's necessary to calculate future scenarios, be it difficult or not.

World climate and the earth magnet field both are complex but this neither means we won't predict them sometime in the future nor that we succeed synchronously to understand them better.

(By the way: Changes in earth's magnet field and in solar activity are mumbo jumbo reasons for climate change lacking scientific evidence, contrary to the greenhouse effect (and mankind's influence on it). According to wikipedia, other reasons caused the ice ages, greenhouse gases among them: Link)

out of curiosity are you like a left-wing enviromentalist? Just wondering

Edit: Flame replaced with a simple :disgust: smiley

 

[Noworkia]

Originally posted by: chcarnage

Originally posted by: Noworkia
How does carbon dioxide trap heat? Does anyone have a link to a model or experiment showing the process on a small scale?

It doesn't "trap" heat in the form of preventing it from leaving the earth, it absorps solar radiation of a certain wavelength and gets warmer. According to this calculation based on quantum mechanics, CO2 currently is responsible for up to 12% of the greenhouse effect.
?

Actually, I was looking for something like a science fair project. Which when I search for science fair, I found what I was looking for.

http://www.fellowshipch.org/pcasftim02.html

Atmosphere Time for Temperature to Rise to 40C Time for Temperature to Lower to 19C
Normal Air .............1 hr. 45 min..................................... 2 hr.
50% CO2 ...............2 hr. ..............................................2 hr. 45 min.
100% CO2 ............2 hr. 15 min.................................... 2 hr. 30 min.

So it appears that pure CO2 doesn't change its energy state as fast as normal air.

 

[f95toli]

OK, but that data is only related to the specific heat of the different mixtures of gas.
It is not directy related to the greenhouse effect or global warming.

 

[Noworkia]

Originally posted by: f95toli
OK, but that data is only related to the specific heat of the different mixtures of gas.
It is not directy related to the greenhouse effect or global warming.

Why not?
What is the experiment then, that I can use to measure the temperature different between a high CO2 content atmosphere and a CO2 absent atmosphere?

I am thinking of this for an experiment for my kid. My idea is to build two air tight boxes from Plexiglas. One filled with CO2 and the other filled with nitrogen. I will place temperature probes in each box and one temperature probe outside the box. I will place the boxes in my back yard. A computer will record and plot all three temperatures over several days. I expect that the CO2 filled box to have a higher average temp than the nitrogen filled box and the probe outside the boxes.

 

[chcarnage]

Originally posted by: Noworkia

Originally posted by: chcarnage

Originally posted by: Noworkia
How does carbon dioxide trap heat? Does anyone have a link to a model or experiment showing the process on a small scale?

It doesn't "trap" heat in the form of preventing it from leaving the earth, it absorps solar radiation of a certain wavelength and gets warmer. According to this calculation based on quantum mechanics, CO2 currently is responsible for up to 12% of the greenhouse effect.
?

Actually, I was looking for something like a science fair project. Which when I search for science fair, I found what I was looking for.

http://www.fellowshipch.org/pcasftim02.html

Atmosphere Time for Temperature to Rise to 40C Time for Temperature to Lower to 19C
Normal Air .............1 hr. 45 min..................................... 2 hr.
50% CO2 ...............2 hr. ..............................................2 hr. 45 min.
100% CO2 ............2 hr. 15 min.................................... 2 hr. 30 min.

So it appears that pure CO2 doesn't change its energy state as fast as normal air.

The conclusion that because pure CO2 doesn't heat up as fast as air, CO2 isn't to blame for greenhouse effect, isn't correct. The reason why? CO2 can only absorb solar energy of a certain wavelength. In a 100% CO2 environment the absence of other gases who absorb other wavelengths neutralizes the additional warming effect by CO2 because the sunrays with CO2-compatible wavelengths are limited.

The relation between CO2 concentration and greenhouse effect isn't a linear function. There is a tipping point with a CO2 concentration of perhaps a few percents where the greenhouse effect is maximal. This graph implies that the absence mostly of O2 and O3 is to blame for the longer heat up time of the 100% CO2 concentration in the experiment.

But there's very little CO2 in the athmosphere and under this circumstances a rise in the CO2 concentration means a bigger greenhouse effect. CO2 being responsible for up to 12% of the greenhouse effect is spectacular if you consider that the CO2 concentration in the athmosphere is only 0.038% by volume!

 

[Noworkia]

Originally posted by: chcarnage

Originally posted by: Noworkia

Originally posted by: chcarnage

Originally posted by: Noworkia
How does carbon dioxide trap heat? Does anyone have a link to a model or experiment showing the process on a small scale?

It doesn't "trap" heat in the form of preventing it from leaving the earth, it absorps solar radiation of a certain wavelength and gets warmer. According to this calculation based on quantum mechanics, CO2 currently is responsible for up to 12% of the greenhouse effect.
?

Actually, I was looking for something like a science fair project. Which when I search for science fair, I found what I was looking for.

http://www.fellowshipch.org/pcasftim02.html

Atmosphere Time for Temperature to Rise to 40C Time for Temperature to Lower to 19C
Normal Air .............1 hr. 45 min..................................... 2 hr.
50% CO2 ...............2 hr. ..............................................2 hr. 45 min.
100% CO2 ............2 hr. 15 min.................................... 2 hr. 30 min.

So it appears that pure CO2 doesn't change its energy state as fast as normal air.

The conclusion that because pure CO2 doesn't heat up as fast as air, CO2 isn't to blame for greenhouse effect, isn't correct. The reason why? CO2 can only absorb solar energy of a certain wavelength. In a 100% CO2 environment the absence of other gases who absorb other wavelengths neutralizes the additional warming effect by CO2 because the sunrays with CO2-compatible wavelengths are limited.

The relation between CO2 concentration and greenhouse effect isn't a linear function. There is a tipping point with a CO2 concentration of perhaps a few percents where the greenhouse effect is maximal. This graph implies that the absence mostly of O2 and O3 is to blame for the longer heat up time of the 100% CO2 concentration in the experiment.

But there's very little CO2 in the athmosphere and under this circumstances a rise in the CO2 concentration means a bigger greenhouse effect. CO2 being responsible for up to 12% of the greenhouse effect is spectacular if you consider that the CO2 concentration in the athmosphere is only 0.038% by volume!

I didn't say that "because pure CO2 doesn't heat up as fast as air, CO2 isn't to blame for greenhouse effect". I noticed that CO2 retains it energy better. That should allow for higher average temperatures, such as at night. You are only looking at half the equation or half of a 24 hour period.

The graphs is interesting but the points at with most of the energy is absorbed by CO2, the absortion rate is already in the 95%+ of energy outside the atmosphere at the same frequency. So, would an increase of 5% in those notches even make dent in total energy absorbed across the entire frequency spectrum?

 

[zephyrprime]

Originally posted by: Parkre
Now multiply everything: Billions of Cars, 6 billion humans, 1000s of powerplants, 10,000s factories, the list goes on. And you know what people? That heat has to go somewhere. To our rivers, oceans, and air.

NOW include all the black asphalt, across the world, all the concrete, buildings, everything.


Put everything together and what do you get? The real reason for global warming.
P

The amount of net energy produced by human activities is actually pretty small.

Refer to here: here

I ran the numbers and for 1995, the energy put out by all fossil fuels is only 0.008899074% of the energy hitting the surface of the earth from the sun. (unfortunately, this calculation doesn't include nuclear energy because I'm too lazy to find that figure.)

 

[chcarnage]

Originally posted by: Noworkia

Originally posted by: chcarnage

Originally posted by: Noworkia

Originally posted by: chcarnage

Originally posted by: Noworkia
How does carbon dioxide trap heat? Does anyone have a link to a model or experiment showing the process on a small scale?

It doesn't "trap" heat in the form of preventing it from leaving the earth, it absorps solar radiation of a certain wavelength and gets warmer. According to this calculation based on quantum mechanics, CO2 currently is responsible for up to 12% of the greenhouse effect.
?

Actually, I was looking for something like a science fair project. Which when I search for science fair, I found what I was looking for.

http://www.fellowshipch.org/pcasftim02.html

Atmosphere Time for Temperature to Rise to 40C Time for Temperature to Lower to 19C
Normal Air .............1 hr. 45 min..................................... 2 hr.
50% CO2 ...............2 hr. ..............................................2 hr. 45 min.
100% CO2 ............2 hr. 15 min.................................... 2 hr. 30 min.

So it appears that pure CO2 doesn't change its energy state as fast as normal air.

The conclusion that because pure CO2 doesn't heat up as fast as air, CO2 isn't to blame for greenhouse effect, isn't correct. The reason why? CO2 can only absorb solar energy of a certain wavelength. In a 100% CO2 environment the absence of other gases who absorb other wavelengths neutralizes the additional warming effect by CO2 because the sunrays with CO2-compatible wavelengths are limited.

The relation between CO2 concentration and greenhouse effect isn't a linear function. There is a tipping point with a CO2 concentration of perhaps a few percents where the greenhouse effect is maximal. This graph implies that the absence mostly of O2 and O3 is to blame for the longer heat up time of the 100% CO2 concentration in the experiment.

But there's very little CO2 in the athmosphere and under this circumstances a rise in the CO2 concentration means a bigger greenhouse effect. CO2 being responsible for up to 12% of the greenhouse effect is spectacular if you consider that the CO2 concentration in the athmosphere is only 0.038% by volume!

I didn't say that "because pure CO2 doesn't heat up as fast as air, CO2 isn't to blame for greenhouse effect". I noticed that CO2 retains it energy better. That should allow for higher average temperatures, such as at night. You are only looking at half the equation or half of a 24 hour period.

The graphs is interesting but the points at with most of the energy is absorbed by CO2, the absortion rate is already in the 95%+ of energy outside the atmosphere at the same frequency. So, would an increase of 5% in those notches even make dent in total energy absorbed across the entire frequency spectrum?

I didn't look at the retain capabilities of CO2 because I considered it less important for the greenhouse effect because its athmospherical concentration is very low. I don't know if CO2 plays a role as heat storage but I don't think so.

The graph question is good, I can't answer it with my means. Maybe more CO2 means that a broader range of solar radiation gets absorbed (turning the spikes in the graph into more U-shaped forms) There could be certain wavelengths where CO2 absorption is present but inefficient (therefore requiring a higher CO2 concentration). Complicated stuff, heh.

 

[xanis]

The sun puts out infinitely more heat than industrial production, and the greenhouse effect causes most of the heat, not that generated by cars and such.

Also, our atmosphere gets colder the higher it goes, correct? So if hot air rises and dissapates in the thin atmosphere, then shouldn't the upper stmosphere get marginally warmer a well?

 

[Cruise51]

There is more to global warming than C02 emissions. "Global Dimming" explains how particulate polution has been counter-acting the greenhouse effect; and why global warming may be a much bigger problem than previously thought.
http://news.bbc.co.uk/2/hi/science/nature/4171591.stm
I couldn't find a download link, sorry.

 

[Noworkia]

What about the solution to global warming? Shouldn't the UN encourage OPEC to reduce oil production 30% to 1990 levels, per the Kyoto treaty? But none of the OPEC members signed the treaty.

 

[Tiamat]

You are partially not correct (at least the way I learned).

It is the CO2 and other greenhouse gases. Normally, heat radiates back out into space. The greenhouse gases do not allow this. So, cars emit heat and the greenhouse gases both working off each other to bring about global warming.

But, this is 9th grade earth science I am falling back on - Im sure there is a much much more detailed description somewhere.