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Post by sigurdur on Mar 14, 2017 21:08:08 GMT
Yep.
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Post by nautonnier on Mar 15, 2017 2:30:11 GMT
Normal heat conduction in gases is by exchange of kinetic energy as discussed in the paragraphs above. That is where you will get lots of papers. However, latent heat is not kinetic energy it is 'vibrational or rotational energy' of a water molecule. This is not the cue ball hitting the 8 ball transferring kinetic energy. The rotational and vibrational energy transfer is not discussed, apart from as a release of photons of infrared 'radiant energy' that can be absorbed by other gas molecules that absorb that frequency of radiant energy.
I find it frustrating that there are lots of papers on heating and storing of latent heat but I have not found a detailed breakdown of how the latent heat is released apart from several sources showing the infrared radiation. Conduction - the sensible transfer of kinetic energy by collision as you state is discussed in some detail.
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Post by sigurdur on Mar 15, 2017 2:53:38 GMT
I don't think the mechanism of latent heat is actually well understood. We know it is there, but we really don't know WHY it is there.
We know pretty exactly when it happens, (is observable)....but that is about it.
There was a person who denied the properties of this heat on the board for awhile. He was a smart feller, but I will state that it is hard to wrap ones head around.
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Post by icefisher on Mar 15, 2017 5:18:56 GMT
I don't think the mechanism of latent heat is actually well understood. We know it is there, but we really don't know WHY it is there. We know pretty exactly when it happens, (is observable)....but that is about it. There was a person who denied the properties of this heat on the board for awhile. He was a smart feller, but I will state that it is hard to wrap ones head around. One might say in theoretical science everybody learns a lot of bad habits. Thus the most adamant deniers of new discoveries are those with the worst learned bad habits.
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Post by Ratty on Mar 15, 2017 6:09:34 GMT
[ Snip ] One might say in theoretical science everybody learns a lot of bad habits. Thus the most adamant deniers of new discoveries are those with the worst learned bad habits. You might also say "with the best learned bad habits" .....
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Post by duwayne on Mar 15, 2017 20:29:04 GMT
The exact molecular mechanism of latent heat release would be interesting but it is less important for the discussion than the result that upon condensation the latent heat of water vapor converts to sensible heat.
Cloud dynamics show that the increase in sensible heat from the condensation of water vapor is equal to the release of latent heat.
On a directly measurable laboratory scale a simple water distillation column shows that the amount of sensible heat which must be removed to condense water equals the latent heat of the water vapor plus the sensible heat of the water vapor above the boiling point. The reverse is true as well. The amount of sensible heat that must be added to water to convert it to steam is the amount to heat it to its boiling point plus an amount equal to the latent heat of vaporization.
Nautonnier, I've already noted that there are something like 40,000 billion billion molecules in the volume of air equivalent to a basketball in response to your concern about the likelihood of a water vapor molecule finding another molecule with which to exchange sensible heat. I've now done a calculation which shows on average a molecule in the air collides with other molecules several million times per second. If anyone is interested or wants to check my math, I'll provide more detail.
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Post by icefisher on Mar 15, 2017 21:40:58 GMT
yes i would say there is a massive amount of conduction taking place from the results. i have heard there are lots of collisions the moist lapse rate is a lot lower (~60% on average) due to the release of latent heat. Since quite damp air is only about 4% water its conducting a lot of heat to the air with the cloud tops pretty much signalling the zone that the latent heat has largely been all released. i would also assume that in the most extreme moist convective environments this would be at the tropopause.
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Post by duwayne on Mar 16, 2017 18:02:54 GMT
I was thinking about why someone might envision molecular collisions as not happening often. A water vapor molecule is about 2.75 angstroms in diameter. The molecules in air at sea level pressure on average are about 40 angstroms apart. So in molecular terms there is a lot of space between the molecules. Why would there be a lot of collisions?
The answer is that molecules move continuously and rapidly. The average speed of a molecule in air is about 500 meters per second. In measurements more related to molecules that's 5 trillion angstroms per second. So it doesn't take long for a molecule to cover the empty space.
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Post by Ratty on Mar 16, 2017 22:12:32 GMT
First ...... Are there any lab experiments that may have answered the questions posed on this thread?
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Post by sigurdur on Apr 8, 2017 15:35:34 GMT
onlinelibrary.wiley.com/doi/10.1002/2015GL066749/fullCO2 is the strongest anthropogenic forcing agent for climate change since preindustrial times. Like other greenhouse gases, CO2 absorbs terrestrial surface radiation and causes emission from the atmosphere to space. As the surface is generally warmer than the atmosphere, the total long-wave emission to space is commonly less than the surface emission. However, this does not hold true for the high elevated areas of central Antarctica. For this region, the emission to space is higher than the surface emission; and the greenhouse effect of CO2 is around zero or even negative, which has not been discussed so far. We investigated this in detail and show that for central Antarctica an increase in CO2 concentration leads to an increased long-wave energy loss to space, which cools the Earth-atmosphere system. These findings for central Antarctica are in contrast to the general warming effect of increasing CO2.
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Post by mondeoman on Apr 8, 2017 17:01:55 GMT
onlinelibrary.wiley.com/doi/10.1002/2015GL066749/fullCO2 is the strongest anthropogenic forcing agent for climate change since preindustrial times. Like other greenhouse gases, CO2 absorbs terrestrial surface radiation and causes emission from the atmosphere to space. As the surface is generally warmer than the atmosphere, the total long-wave emission to space is commonly less than the surface emission. However, this does not hold true for the high elevated areas of central Antarctica. For this region, the emission to space is higher than the surface emission; and the greenhouse effect of CO2 is around zero or even negative, which has not been discussed so far. We investigated this in detail and show that for central Antarctica an increase in CO2 concentration leads to an increased long-wave energy loss to space, which cools the Earth-atmosphere system. These findings for central Antarctica are in contrast to the general warming effect of increasing CO2. Oooh thats gonna hurt.
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Post by icefisher on Apr 8, 2017 17:13:20 GMT
onlinelibrary.wiley.com/doi/10.1002/2015GL066749/fullCO2 is the strongest anthropogenic forcing agent for climate change since preindustrial times. Like other greenhouse gases, CO2 absorbs terrestrial surface radiation and causes emission from the atmosphere to space. As the surface is generally warmer than the atmosphere, the total long-wave emission to space is commonly less than the surface emission. However, this does not hold true for the high elevated areas of central Antarctica. For this region, the emission to space is higher than the surface emission; and the greenhouse effect of CO2 is around zero or even negative, which has not been discussed so far. We investigated this in detail and show that for central Antarctica an increase in CO2 concentration leads to an increased long-wave energy loss to space, which cools the Earth-atmosphere system. These findings for central Antarctica are in contrast to the general warming effect of increasing CO2. Yes I think thats right. The arctic is not warmer because of CO2 its warmer because of the loss of the insulating layer of sea ice. The loss of sea ice can potentially be attributable to the loss of clouds (Svensmark?) and thus more sunlight reaching the sea ice surface. Since most of the warmest atmospheric conditions in the Arctic are during winter and the coolest in the summer. Yet the opposite is true for the ice winter sea ice is much closer to its mean than summer sea ice has been strongly suggesting the net greenhouse effect is very minor in relationship to cloud changes since sunlight changes have very little effect in the winter.
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Post by sigurdur on Apr 8, 2017 17:31:45 GMT
Both poles have the same effect in regards to cooling. It takes awhile to warm an engine, it takes awhile to cool an engine.
When the troposphere is a few 1,000 feet thick, that "insulating" blanket is damn thin!
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Post by nautonnier on Apr 8, 2017 21:33:23 GMT
onlinelibrary.wiley.com/doi/10.1002/2015GL066749/fullCO2 is the strongest anthropogenic forcing agent for climate change since preindustrial times. Like other greenhouse gases, CO2 absorbs terrestrial surface radiation and causes emission from the atmosphere to space. As the surface is generally warmer than the atmosphere, the total long-wave emission to space is commonly less than the surface emission. However, this does not hold true for the high elevated areas of central Antarctica. For this region, the emission to space is higher than the surface emission; and the greenhouse effect of CO2 is around zero or even negative, which has not been discussed so far. We investigated this in detail and show that for central Antarctica an increase in CO2 concentration leads to an increased long-wave energy loss to space, which cools the Earth-atmosphere system. These findings for central Antarctica are in contrast to the general warming effect of increasing CO2. "CO2 is the strongest anthropogenic forcing agent for climate change since preindustrial times. "Extremely poorly written and a failed hypothesis. This is an assumption and every attempt to build a non-falsified hypothesis for the real atmosphere has failed. CO2 can 'scatter' infrared and if while it is still excited after an infrared photon has hit it, it can provide some kinetic energy 'temperature' to Nitrogen and Oxygen molecules. It is far more likely that a CO2 molecule will receive kinetic energy from collisions and radiate that energy than it is to be hit by an infrared photon in consequence as CO2 is added to a volume of atmosphere that volume of atmosphere will radiate infrared whereas a volume without CO2 would not (well orders of magnitude less strongly) as Nitrogen and Oxygen are 'non-radiative' gases. In previous epochs the atmosphere has had ten times as much CO2 in the atmosphere and the Earth had no catastrophic warming (we are still here). Indeed proxies seem to show that the temperatures reach a level and then go no further. Just as now the tropical oceans have a top temperature of 31C that is not exceeded as feedbacks from storms and cloud cover reduce the high frequency sunlight input (see 'Earth's Iris) and provide convective heat loss. As we have discussed before infrared striking the surface of water which is about 70% of the Earth's surface, cool the surface by increasing evaporation and the surface loses latent heat of evaporation which is then carried upward in the atmosphere and released at height as the water vapor first condenses and then freezes. The incoming air to replace the convective updraft greatly increases the evaporation and therefore the evaporative loss of latent heat of evaporation. Convective heat loss is huge dwarfing anything mankind can do. The convective and latent heat transport in a standard hurricane per day is more than 200 times the worldwide electricity generation capacity. ( www.aoml.noaa.gov/hrd/tcfaq/D7.html) So Cyclone Debbie that just dampened Ratty and stayed as greater than Cat 2 for say 5 days took energy equivalent to more than 1000 times the electricity generation capacity of the world out of the ocean East of Queensland. Now consider the energy that was required by the storms that crossed the USA last week and had a center of circulation around the Ohio valley and the squall lines and severe storms stretched from the Gulf of Mexico to New England. I am coming to the conclusion that there is no such thing as 'the greenhouse' effect. Has anyone got any ' conclusive observational evidence' that would suggest that a 'green house effect' exists?
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Post by acidohm on Apr 8, 2017 21:46:38 GMT
Naut, i feel you have far more to teach me then i you....however the vid I posted on climate science thread recently shows using basic physics the disparity between the expected surface temp of our planet with no atmosphere, and the surface temp including atmosphere, and there's about ( from memory) a -30°c difference. Ie, there is a warming effect being exerted on the surface beyond the incoming solar radiation. Well, an insulating effect really because the energy into our planet must equal the energy out or we would be warming, and not necessarily by fractions of a degree over a century (where it is dubious we could measure such a thing through history anyway!!)
Best watch the vid...the professor is an expert....i am not!!
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