Discussion > Keeping it simple
Dulac,
Finding a definition of GE that does not include a controversial statement is proving to be elusive.
Would you be minded to suggest one?
Belle Epoque
BE: “greenhouse effect” is really a misnomer, as greenhouses merely prevent the distribution of heat away from the locale by convection – easily demonstrated by opening up any windows, and seeing how rapidly it can cool. However, convection is an important factor in the distribution of heat throughout the atmosphere, thus it is not really “greenhouse effect” that is keeping the atmosphere warm (though a blanket of cloud can slow down the rate of loss of heat, at night – whether that could be called “greenhouse effect” or “blanket effect” is a moot point. Whatever it is named, it is the only incontrovertible evidence that the atmospheric composition – i.e. higher concentrations of H2O (water) molecules – might have some effect). While “greenhouse gases” can be shown to absorb certain wavelengths of the electromagnetic spectrum, it is not known how this effect can affect the somewhat less-controlled environment outside the laboratory.
Looking to Venus, it would appear that CO2 has very little effect, as the atmosphere of Venus is around 98% CO2, yet the temperature of the Venusian atmosphere at altitudes where the pressure is at Earth-equivalent is the same as the temperature on Earth would be, were we the same distance from the Sun as Venus is. The oft-quoted “environmental climate sensitivity” (ECS) is usually said to be 1°C per doubling of CO2 (however, this is not proven, and some claim up to 8°C); if this were true, then the Venusian temperatures should be at least 11°C (or even as much as 88°C) higher than they are, now (98% being a little over 11 “doublings” of our present CO2 concentration of 0.04%).
Radical Rodent
BE: “greenhouse effect” should really be called "climate stabiliser effect" or similar.
Water in the form of vapour is by far the most influential warming gas in the atmosphere.
It is acknowledged by all scientific bodies.
Just look at the difference in daily temperatures today:
TIMBUKTU: http://www.bbc.co.uk/weather/2449067
has a daily variation of 37 degrees down to 18 degrees C with a humidity of 5%.
MANAUS: http://www.bbc.co.uk/weather/3663517
has a daily variation of 28 degrees down to 24 degrees C with a humidity of 84%
The main differences between the two locations: MANAUS is a town in a jungle, TIMBUKTU is a town in a desert.
But look at the differences in humidity!
It is dramatic.
Lets assume CO2 is well mixed and similar around the earth ( I know, I know)
The main variable is water vapour, clouds, rain and any other form of water, constantly responding to changing wind and sun. It dwarfs CO2 in its effects.
I think it is fair to say that without water, the daily temperature variation experienced on earth would make it inhospitable for life. (disregarding our necessary need for water to drink and crop use).
Steve Richards
Mar 9, 2017 at 7:31 PM | dulac
Would you be minded to suggest one?
Mar 10, 2017 at 10:24 AM | Belle Epoque
The biggest Forcings in Climate Science, have come from the failures representing 97% of Climate Science, trying to force their theories on the entire world.
Trump is proposing to do away with 97% of Climate Scientists and further discussion of their failures, and the whole world can benefit by tens of billion€£$ per year.
Expecting the 3% of Climate Scientists (and others with a personal and/or technical interest) to come to the rescue of the 97% now, when the 97% have invested a lot of other people's money in excluding them for 20 years, does seem curious timing.
golf charlie
Mar 10, 2017 at 1:39 PM | golf charlie
Criticism of Belle Epoque's question NOT intended.
golf charlie
@RadicalR @SteveR
Perhaps we should do a BBC fence-sit and say 'so called greenhouse effect'.
But you are right to point out that we have a badly named effect of a poorly described phenomena to which I would add that attracts a reaction disproportionate to evidence on the basis that a section of society subscribes to the precautionary principle which is, at best, an anti-progress charter.
Belle Epoque
Mar 10, 2017 at 2:30 PM | Belle Epoque
20 years without taxpayer funding should be sufficient to establish whether it is worth worrying about whether it is worth worrying about for a further 20 years.
Hockey Teamster theories don't stand the test of time, and no one can stand the Hockey Teamsters.
golf charlie
Belle Epoque
Looking around the internet, it's amazing how many 'definitions' of the greenhouse effect not only include a purported explanation of its action but one which is simply wrong. For example Wikipedia:
The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without its atmosphere.
Much the same as my claiming that heat emitted by my wall insulation warms the interior of my house. Wikipedia attributes it to the IPCC.
I sent a request to the Met Office:
I would be grateful if you would provide, or point to where I can find, a simple definition of the greenhouse effect. In particular, I would like a definition that does *not* also include an explanation of the mechanism(s) by which the greenhouse effect operates.
Their reply, although not exactly what I had asked for, does go some way to being a mechanism-free definition of the GHE:
"The effect, analogous to that which has been supposed to operate in a greenhouse, whereby the earth’s surface is maintained at a much higher temperature than the temperature (about 256 K) appropriate to balance conditions with the solar radiation reaching the earth’s surface....
That seems to me to be a mechanism-free definition. They then continue:
....The atmospheric gases are almost transparent to incoming solar radiation, but water vapour and carbon dioxide in the atmosphere strongly absorb long wave radiation emitted from the earth’s surface and re-emit the radiation, in part downwards. Chlorofluorocarbons (CFCs) and methane also make a contribution to the greenhouse effect which is becoming of increasing significance."
Martin A
Marin A. That seems to me to be a mechanism-free definition.
Except they use the word 'surface' which then leads them to their description of a mechanism. The 33 degK of the GE is not a surface measurement, not the Stevenson Screen part anyway. Their definition is, therefore, controversial.
With the same skeleton of the MO sentence but with facts correct and a magnitude to nail it down;
GE: an average temperature distribution in an atmosphere where near-surface temperatures are higher than the planet's radiating temperature to space. On Earth, that difference is 33 degrees Celsius.
Seams to me to be concise, accurate, bias/mechanism-free and shows its benign effect rather than hitching it to doomsday scenarios.
Belle Epoque
And an impressive list of physical effects that you have managed to recall.
If you wish to denote "work" as any transfer of energy from one place to another or transformation of energy from one form to another, including photo emission of electrons, and on scales from quantum scale to macroscopic, you have the right to do so, as I said previously.
But you delude yourself if you think that your idiosyncrasy is widely shared. The world at large, contrary to your belief, reserves the term "work" for force multiplied by the distance through which the point of application of the force moves.