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#27389 - 07/31/08 02:53 AM Greenhouse Effect
sunnye
Unregistered


The average temperature of the earth's surface is about 15C (59F). The temperature largely is determined by the amount of energy absorbed from the sun versus the amount of energy emitted into space by the earth. The energy absorbed by the sun mainly covers wavelengths from the ultraviolet (< 400 nm) through the visible (400 to 700 nm) though the ultraviolet (> 700 nm).
Any change in the balance between the quantity of energy absorbed compared to the amount emitted affects climate. The "greenhouse effect" is concerned with the infrared radiation given off by the earth. Part of this radiation is absorbed by the atmosphere, rather than being lost to space. The gases in the atmosphere that absorb infrared light primarily are water (H2), carbon dioxide (CO2), ozone (O3), nitrous oxide (NO2) and methane (CH4). The gases act as a sort of insulating blanket for the earth, in the same way they would act to lessen heat loss from a greenhouse, hence the name 'greenhouse effect'. It is estimated that the mean global surface temperature of the earth would be -25C (-13F) if not for the absorption of energy by carbon dioxide and water.
The concentration of water vapor in the atmosphere is higher than that of carbon dioxide. Consequently, most of this energy conservation is attributable to water. You can see this effect when you look at how temperature drops less on nights with heavy cloud cover as opposed to clear skies or when you consider how large the temperature difference between day and night is in places with lower relative humidity, like the desert.
Although the concentration of carbon dioxide in the atmosphere is low (~375 ppm in 2005), it has been increasing appreciably over time. A century ago, the carbon dioxide concentration was less than 300 ppm. Human activites are accountable for this increase, including consumption of fossil fuels and extensive clearing of land (less carbon dioxide can be consumed by photosynthesis). Changes in the levels of carbon dioxide in the atmosphere are associated with changes in the earth's climate

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#27394 - 07/31/08 04:34 AM Re: Greenhouse Effect [Re: ]
samwik Offline
Megastar

Registered: 10/10/06
Posts: 1164
Loc: Colorado
Thanks Sunnye, for your excellent overview of the GH effect.

One thing most folks don't realize is that the "heat" lost to space is in the range of below-zero temperatures.
The heat that we experience here at the surface is radiated up and translated through collisions (decaying to lower temperatures) to the upper reaches of the atmosphere (eventually) where it can then be radiated away (if the narrow windows allowing certain wavelengths to escape are still open).
...or words to that effect. wink
I think this is accurate. Someone let me know if there's a question or correction.

If your interested, you might check out:
"Human Influence on Climate" for a spirited and scientifically detailed discussion of the physical mechanism of IR absorption by CO2 (and other gases) and the "greenhouse effect."
http://www.scienceagogo.com/forum/ubbthreads.php?ubb=showflat&Number=26091#Post26091

Thanks,
~ smile

p.s. Nitrous oxide, commonly know as "laughing gas", is a chemical compound
with the
chemical formula N2O. -wikipedia
NO2 (nitrogen dioxide) is something else... technicalities.


Edited by samwik (07/31/08 04:57 AM)
Edit Reason: add p.s.
_________________________
Pyrolysis creates reduced carbon! ...Time for the next step in our evolutionary symbiosis with fire.

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#27707 - 09/12/08 09:09 PM Re: Greenhouse Effect [Re: ]
blake
Unregistered


Something to Cheer for us.Atlast China realised the effects of greenhouse but we should first congratulate the Olympics organisers for organising games in china which made China to stop emission of green house gases.....................
james blake
california dui

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#27738 - 09/14/08 10:03 PM Re: Greenhouse Effect [Re: ]
annonyed mouse Offline
Junior Member

Registered: 09/14/08
Posts: 4

Wernt they forced to clean up their emissions?
Shut down the factorys and took most cars of the streets, since you couldnt see clearly for the smog.

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#27739 - 09/14/08 10:06 PM Re: Greenhouse Effect [Re: annonyed mouse]
annonyed mouse Offline
Junior Member

Registered: 09/14/08
Posts: 4

Or breath properly. The atheletes would have boycotted the games if they hadnt done something about that

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#27747 - 09/15/08 02:03 AM Re: Greenhouse Effect [Re: ]
samwik Offline
Megastar

Registered: 10/10/06
Posts: 1164
Loc: Colorado
Originally Posted By: blake
Something to Cheer for us. At last China realised the effects of greenhouse but we should first congratulate the Olympics organisers for organising games in china which made China to stop emission of green house gases.....................
james blake


Just fyi,

I hope you realize this change was on the order of 1% (or less) of their total pollution and was only for a few weeks to a month.

It would be interesting to look at the regional/global data and see if a signal of that small change could be picked up; but in terms of a change for the better, I don't think there is anything to cheer about. It's all back to business as usual by now.

And more specifically, you are confusing greenhouse gases with smog-like pollution.
GHG's are invisible and affect the temperature, not breathing or vision.

Soot, other particulates, nitrogen oxides, sulfur oxides, ozone, polycyclic and non-cyclic hydrocarbons, etc. are the pollutants that affect vision and breathing, and health in general, etc.

CO2 is often produced by the same processes that generate these other pollutants, so cleaning up one often affects the other, but they are different things with different effects.

smile
_________________________
Pyrolysis creates reduced carbon! ...Time for the next step in our evolutionary symbiosis with fire.

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#28793 - 12/11/08 08:44 PM Re: Greenhouse Effect [Re: samwik]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
China could REALLY use some scrubbers in their stacks to remove most of the particulate pollution , and if they dont shut them down at night ( because at night its hard to SEE the pollution ) the way they do here in america at night , they could at least have a cleaner environment for our products to be built in.

if you didnt already know , here is a reference ! to a scrubber manufacturer.

_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#30773 - 05/25/09 02:34 AM Re: Greenhouse Effect [Re: paul]
henrymaquli
Unregistered


There is nothing called a free lunch is this world. If things needed to be resolved then initiative needs a support to be sorted out.
as we are growing our technology we are destroying our nature and some adverse effect are coming out through nature, it's one of them.
Global warming is happening now. There has been an increase in extreme weather events over the past 20 years such as floods and droughts resulting in failed harvests, destroyed homes and a deepening health crisis for millions of the world's most vulnerable people.
henrymaquli
dui


Edited by henrymaquli (05/25/09 02:36 AM)

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#30782 - 05/25/09 10:30 PM Re: Greenhouse Effect [Re: ]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
There is nothing called a free lunch is this world.


You cannot reach down and pull yourself up by your boot straps.

but you can use a simple mechanical advantage to do the job much cheaper.

then the money you save can buy the free lunches.
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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